Presumably you are talking about Windows File Explorer and not the Explorer window in Vegas in which case you might get more response by posting in a Windows forum.

Hi, I thought I pointed out that it was file explorer in Windows 11 and mentioned that the thumbnails for the.MOV video files do work in Vegas explorer.....

I already went through the Windows forum route and have not found a fix, I figured that I might have better luck asking people who deal with video files all the time in Windows since they might have come across this issue at one point or another. I noticed this problem after the last Vegas 19 update so I thought maybe that was the cause, but Vegas codecs and such are usually self-contained to Vegas so it is more likely something else.

Thanks. I just wanted to check as if it's not a Vegas Pro problem it's proper to the Offtopic area so I'll move it.

@Richvideo

Do you have Quicktime loaded? Can you play the file with a native Windows application like Movies & TV?

Vegas doesn't need Quicktime to decode some files with the MOV extension depending on the codecs used inside the wrapper.

My SWAG

Windows doesn't have a codec to use to scan into the file and find a frame to use as the thumbnail. If you associate the extension with a player that can play the file, you'll get the thumbnail of the application. That won't be much help because it won't give you a hint of what's in the file. I won't comment on a codec pack.

I just did a clean install of Windows 11 a few weeks ago.
Installing K-Lite codec pack is a terrible idea - I would uninstall that if I was you!
It can wreck your Windows Registry and stop good codecs from working.
You shouldn't need to be using K-lite codec pack in 2022.

I do use Icaros (by itself) on my new Windows 11 install and all .mov video thumbnails are working in W11.

Download latest version of Icaros 3.2.1 from here:
https://www.videohelp.com/software/Icaros

Open Icaros 3.2.1
Drag one of the .mov files into the top window of Icaros
You should see the thumbnail generate immediately.
Make sure you have Icaros activated.
 

@Richvideo

Do you have Quicktime loaded? Can you play the file with a native Windows application like Movies & TV?

Vegas doesn't need Quicktime to decode some files with the MOV extension depending on the codecs used inside the wrapper.

My SWAG

Windows doesn't have a codec to use to scan into the file and find a frame to use as the thumbnail. If you associate the extension with a player that can play the file, you'll get the thumbnail of the application. That won't be much help because it won't give you a hint of what's in the file. I won't comment on a codec pack.

I have QT installed, I don't have any issues playing the files in any player ((MPC,VLC WMP Movies & TV), Windows is just not generating a thumbnail preview for the Panasonic 4K 10 bit AVC files with a MOV extension - I could be recalling incorrectly but I am pretty sure I had thumbnails in file explorer for these files previously - as I have stated before, I have thumbnails in Vegas 19 the issue is just getting them to pop up in Windows, MP4s are creating thumbnails in file explorer.

This makes it hard to figure out what files I want to drag over to Vegas because I can't see the thumbnail preview

I just did a clean install of Windows 11 a few weeks ago.
Installing K-Lite codec pack is a terrible idea - I would uninstall that if I was you!
It can wreck your Windows Registry and stop good codecs from working.
You shouldn't need to be using K-lite codec pack in 2022.

I do use Icaros (by itself) on my new Windows 11 install and all .mov video thumbnails are working in W11.

Download latest version of Icaros 3.2.1 from here:
https://www.videohelp.com/software/Icaros

Open Icaros 3.2.1
Drag one of the .mov files into the top window of Icaros
You should see the thumbnail generate immediately.
Make sure you have Icaros activated.
 

I have that version of Icaros installed and it did not fix the issue

I have been using the K-Lite for years with no issues- Vegas uses its own set of codecs so K-lite has no way to impact it.

You can also always re-register the Windows media foundation codecs

I like the MPC player a bit better than VLC and K-lite has its own version of it and I use a Plug-in for it that does a nice job with playing back HDR files. K-Lite also installs the same version of Icaros (I uninstalled K-lite and tried just having Icaros installed and that did not help either)

When you say you have thumbnails for .MOV files, is that in Vegas or Windows File Explorer? I can see them in Vegas

Are these files modern 4K h.264/h.265 MOV files or old Legacy QT files?

Thanks for the feedback