iPhone video goes black on camera roll workaround

I noticed a thread about downloading video from iCloud photos, but the downloaded videos only played audio and displayed a blank/black screen. I too was experiencing this issue. The workaround I found was to share the video from the device (in this case, my iPhone 12) to an "album." Make sure you have the "All Photos Data" option checked (tap the share icon, then Options at the top). I opted to "create new album." Then, I chose the download option from the newly-created folder on icloud.com on my PC. It converted the .mov files to .mp4, but the quality was still pretty good.