Hi all,
Newish to both editing and youtube here and have come up against a problem that I haven't been able to work out yet.
My latest creation exhibits distracting white flashes at irregular intervals - here's a link to demonstrate, the flashing effect starts only a second or two into it and can be seen on the timeline too ... 
The original footage is Gopro Hero9 and shows no sign of any flashing - link to one piece of the original footage here, sure hope the link works ... https://1drv.ms/v/s!At26wYO-N7Lfg5U7UhDDDlCfN3lw0w?e=eypLIT
I've setup ready for render a few times now. Prior to the any render there is no flashing showing on the Vegas timeline. After any render it shows up on the timeline and I work out how to remove it - no idea how which setting might have caused it to happen, though I'm a long way from knowing what I'm doing with colours and fx.
I have issues with crashing fairly regularly too.
Sure appreciate any suggestions anyone has, more info below and in signature.
Thanks, Mike
MediaInfo
General Complete name : C:\Users\mikeh\Videos\Vegas Projects\Rendered\Sunshine with Suz Mar 26 ZZZ (8).mp4 Format : MPEG-4 Format profile : Base Media / Version 2 Codec ID : mp42 (isom/mp42) File size : 1.18 GiB Duration : 6 min 59 s Overall bit rate mode : Variable Overall bit rate : 24.1 Mb/s Encoded date : UTC 2021-05-22 06:16:16 Tagged date : UTC 2021-05-22 06:16:16 Video ID : 2 Format : AVC Format/Info : Advanced Video Codec Format profile : High@L5.1 Format settings : CABAC / 4 Ref Frames Format settings, CABAC : Yes Format settings, Reference frames : 4 frames Codec ID : avc1 Codec ID/Info : Advanced Video Coding Duration : 6 min 59 s Bit rate mode : Variable Bit rate : 23.9 Mb/s Maximum bit rate : 48.0 Mb/s Width : 3 840 pixels Height : 2 160 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 29.970 (30000/1001) FPS Standard : NTSC Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 8 bits Scan type : Progressive Bits/(Pixel*Frame) : 0.096 Stream size : 1.17 GiB (99%) Language : English Encoded date : UTC 2021-05-22 06:16:54 Tagged date : UTC 2021-05-22 06:16:54 Color range : Limited Color primaries : BT.709 Transfer characteristics : BT.709 Matrix coefficients : BT.709 Codec configuration box : avcC Audio ID : 1 Format : AAC LC Format/Info : Advanced Audio Codec Low Complexity Codec ID : mp4a-40-2 Duration : 6 min 59 s Bit rate mode : Variable Bit rate : 192 kb/s Maximum bit rate : 457 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Frame rate : 46.875 FPS (1024 SPF) Compression mode : Lossy Stream size : 9.48 MiB (1%) Language : English Encoded date : UTC 2021-05-22 06:16:18 Tagged date : UTC 2021-05-22 06:16:18
Properties
General Name: GH020226.MP4 Folder: C:\Users\mikeh\Videos\SD card downloads 1 Mar to X\Sunshine Mar 26 Type: AVC Size: 2.07 GB (2,122,727,609 bytes) Created: Saturday, March 27, 2021, 1:17:52 AM Modified: Friday, January 1, 2016, 3:34:34 AM Accessed: Tuesday, May 25, 2021, 2:26:57 PM Attributes: Archive Streams Video: 00:02:49.336, 29.970 fps progressive, 3840x2160x32, AVC Audio: 00:02:49.215, 48,000 Hz, Stereo, AAC Summary [TCFM]: 6 ACID information ACID chunk: no Stretch chunk: no Stretch list: no Stretch info2: no Beat markers: no Detected beats: no Other metadata Regions/markers: no Command markers: no Media manager Media tags: no Plug-In Name: so4compoundplug.dll Folder: C:\Program Files\VEGAS\VEGAS Pro 18.0\FileIO Plug-Ins\so4compoundplug Format: AVC Version: Version 1.0 (Build 8532) Company: MAGIX Computer Products Intl. Co.