Windows 10: MP4 thumbnails are not showing anymore. PNG, JPG, etc, work just fine

Since yesterday the thumbnails of my MP4 files are not showing anymore. At first it was only a few, but after trying to fix it, all thumbnails of videos files are gone now. This issue started after I downloaded Sony Vegas Pro 19 but now I have deleted it completely off my PC again but this issue is still here. I had a windows update too at that time which I tried to reset back, with no luck though because resetting kept failing. I tried everything I could find online to fix this:-Changed folder settings-Changed advanded setting-Made sure "always show symbols, never thumbnail" is unchecked-Ran

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MP4s lose thumbnails, but gain icons; AVIs still have thumbnails.

Something happened to my HDD today causing MP4s to lose their thumbnails, but a clone that was made a few days ago, first shows generic icons for the default Player, then after a moment, they turn into thumbnails. I'd like to understand what is going on, and above all, how to make the non-clone show thumbnails again for MP4s.

Much discussion 'on the web' suggests the icon cache may be corrupt so I made the main HDD a slave to the clone which shows the thumbnails satisfactorily, and cleaned out the icon cache, and refilled it with a copy of the clone's cache. NO improvement !

 

Thumbnails no longer generating for .mp4 files

I recently installed and uninstalled a bunch of programs (which I believe caused the issue).

Afterwards, for some reason, only .mp4 files will no longer generate thumbnails in the explorer. Any new .mp4 file I create now shows up as a default blank thumbnail. Existing .mp4 files (before the issue came up) still retained their thumbnails. All other
types of files are showing up fine.

I deleted the thumbnail cache, and all thumbnails regenerated except .mp4 files.

Does anyone know how to fix this issue? Thank you.

 

.mp4 thumbnail icons!?

Did the feature update this morning and now I don't get thumbnail previews for .mp4 files only!

Any idea why anyone!? I like my thumbnails!!!

Chuter.

EDIT: To be more specific it seems it's only not going to show me the .mp4 video thumbnails for the videos that came from my MotoZ2 play device which are in 4k. if that may have anything to do with it?