And please make sure that you follow point C-1 and upload a detailed MediaInfo report on your media.

Here is the all the information requested

1) VEGAS Version & Build = Vegas Pro 19 build 424

2) Windows Edition & Version = Microsoft Windows 10 Pro Version    10.0.19044 Build 19044

3) Camera/App that created your footage = iPhone Xs Max /OS 15.1

4) Exact symptoms of your problem = See original comment.

5) MediaInfo Report for your source footage = See file on my dropbox folder https://www.dropbox.com/sh/somh8xxppz0aivh/AAAh3ivMWVwpbeoP3lV_-3lQa?dl=0

6) Graphics Card Model = I have two Graphics Card bot with current updates.
Name    NVIDIA GeForce GTX 1660 SUPER
Adapter Type    NVIDIA GeForce GTX 1660 SUPER,
Adapter RAM    (1,048,576) bytes
Driver Version    30.0.14.7247
----------------------------------------------
Name    Intel(R) HD Graphics 630
Adapter Type    Intel(R) HD Graphics Family, Intel Corporation compatible
Adapter Description    Intel(R) HD Graphics 630
Adapter RAM    1.00 GB (1,073,741,824 bytes)
Driver Version    30.0.101.1069

e.g. "AMD Radeon RX 580", "NVIDIA GeForce GTX 1070".

7) Status of GPU acceleration of video processing = It is On, I normally allocated between 40-60% for the Dynamic RAM. I used Nvdia, although even switching to the Intel the same problem occurs.

8) Status of Enable Hardware Decoding for supported formats = I don't believe I am using AVC or HEVC. When I did check the decoder in File I/O it shows the following (see image in the dropbox folder link https://www.dropbox.com/sh/somh8xxppz0aivh/AAAh3ivMWVwpbeoP3lV_-3lQa?dl=0

9) Project Properties = see image in drop box folder link https://www.dropbox.com/sh/somh8xxppz0aivh/AAAh3ivMWVwpbeoP3lV_-3lQa?dl=0

10) Render Settings = there is no rendering issues.

11) More information about your PC = refer to original comment.

It's possible to upload pictures directly to the forum- see the arrow next to the smiley face.

Your MediaInfo says you are using variable frame rate AVC.

File i/o settings look good- I also have an i7-7700 and letting the Intel iGPU handle decoding works best. That said, there are reported issues with the newer 30. Intel drivers- I am staying on 27.20.100.9664 until they are resolved.

I do know that you can upload images direct, however each time I tried to upload a small jpg file it kept telling me there was an error uploading so I just uploaded on my dropbox.

I wasn't aware I was use AVC. Thanks. I haven't actually found a big difference between Intel and Nvdia this is why I use Nvidia.

@Steve-Zoicks-Iconic Hi, you can place all those images that you put in the Dropbox straight on here using the arrow next to the smiley face at the top of a new comment, not everyone will want to open Dropbox & the information is here on this thread to easily ref to 👍 Media info, select the Text option, select all, copy then paste in a new comment,

Edit - Roger beat me to it 😂🤷‍♂️

You are using Intel decoding (see file i/o) and NVIDIA for overall and Fx video processing (preferences/video).

@RogerS okay I see that. Still having the issue though?

@Former user refer to my earlier comment

I suggested an earlier Intel driver and gave the version I use.

Beyond that Vegas prefers constant framerate video. Software like Handbrake can do the conversion for you,"swap media files" and see if it helps.

@Steve-Zoicks-Iconic Yep sorry, i think we were all typing at the same time but i'm a 1 finger typer & so last to click 'Comment' 👴😂👍

@RogerS I often use Filmic Pro on our mini iPad and iPhone when filming our clients' work. So I guess since the apple devices are always using VFR handbrake may be an additional thing I will need to do for each clip of footage before importing to Vegas.

Do you ever think Vegas or any video software will actually support VFR in the future? I know that Adobe Premiere never has and they probably never will.

No problem @Former user I understand. Thank you for your input.

@Steve-Zoicks-Iconic Your PC is exactly the same as my old one which i still have, & is partly why i'm interested in this, i7-7700, GTX 1660 SUPER & 64GB Ram, i have an M.2 drive but don't think that makes a huge difference, that machine was running VP18 tho,

At the moment i use 4k AVC 3840x2160 clips straight from my phone which are VFR & play no prob Good - Full in the preview but i'm using a different more powerful PC now so can't really compare, I guess I'm curious as to whether i'm keeping my old PC, rebooting it or just getting rid as i don't use it .. 🤷‍♂️

What is your configuration of your powerful PC @Former user
If you editing straight from your clips into Vegas than it could be my PC?

@Steve-Zoicks-Iconic click on my Signature on this/any comment & it shows my specs, I upgraded from my old PC because it was a bit laggy, but i'm not saying you need to, if you look at a lot of the regulars who comment on here, they haven't got much more than yours. check out Rogers signature 👍 converting to constant frame rate might help a lot,

You can fill yours in if you go to the top, click your icon - Profile, fill in the bit called My signature, it'll help others to help you 👍

@RogerS I often use Filmic Pro on our mini iPad and iPhone when filming our clients' work. So I guess since the apple devices are always using VFR handbrake may be an additional thing I will need to do for each clip of footage before importing to Vegas.

Do you ever think Vegas or any video software will actually support VFR in the future? I know that Adobe Premiere never has and they probably never will.

There's been a sudden influx of questions about iphone video not working well or at all, maybe due to the sales and new Iphone release, I compared Premiere to VP18 in another thread. Premiere scrubbed footage very well, playback smooth, audio in sync. Vegas had problems, but less problems then it used to. Audio stays in sync, with dolbyvision files video now displays, with assistance from GPU decoding for new release IPhone firmware, and without GPU decoding for older dolbyvision files. So there is a tiny bit of progress, will Vegas ever have smooth VFR 4K playback? Surely if Premiere can do it so can Vegas

@Former user Isn't that because iPhones use HEVC as default, or is iPhone 'Compatible' AVC just as bad?

Will have a look at your specs soon @Former user

Thanks @Former user for info.

@Steve-Zoicks-Iconic These are pics from your Dropbox, your project is set to 1920x1080 25fps but your media is 3840x2160 24fps, I don't know if this makes any difference but you might as well have your project the same size as the media, Vegas is still using your 3840x2160 whatever your project is, when you drag the footage in & it asks if you want to change the project to suit the media click yes, you can always render out at whatever aspect ratio you want.

Actually the project is 1080 x 1920, this is portrait mode?

That is weird, as I alway say Yes. I film in 4K 24fps as we are doing quite alot of work on TikTok for our customers. This is why the project is 1080 x 1920.

I might have made a mistake when setting the project media. I don't think this would be that big of a problem though?

@Former user Isn't that because iPhones use HEVC as default, or is iPhone 'Compatible' AVC just as bad?

VFR is a problem on AVC and HEVC files on Vegas. Default on Iphone is still AVC out of the box, but switch on Dolbyvision, and many will, it's a big part of the marketing for the 12 and 13 series iphones the phone then encodes in HEVC. VFR + HEVC + 4K an even bigger headache @Former user

@Steve-Zoicks-Iconic can you put the media in a zipped folder & put it on Dropbox or Google drive, then share the link?

@Former user 👍 I've seen that 'Dolbyvision' mentioned in comments on the net, I don't have an iPhone, i've go a Samsung 🤷‍♂️😂👍