Twitter – Some Twitter GIFs don’t work in PC browsers, do work in mobile browsers

I could really use some help figuring out this very weird issue I have with Twitter GIFs.

Some Twitter animated GIFs (which Twitter converts to MP4s, but I’ll refer to them as GIFs for simplicity’s sake) don’t work in my Windows PC’s Web browsers. This applies to some GIFs and not others – it seems to be something like a 30/70 work/don’t work split – and it affects both Firefox and Chrome on my PC, but not on my Android phone. (This applies to both the main Twitter site and the TweetDeck platform.)

For example, take this first GIF (direct link).

In Firefox on my PC, the GIF preview image loads, but clicking Play makes it go to black. Using the direct link also shows a blank space, with the video progress bar – even though it’s 7 seconds long– stuck at the end and the Play button doing nothing.

In Chrome on my PC, the GIF freezes on the first frame and clicking does nothing; the direct link shows the same as above, with the progress bar stuck.

Yet, in both Firefox and Chrome on my Android phone, the GIF works fine both in the tweet and using the direct link.

Now, take this second GIF (direct link).
It loads perfectly fine in all my browsers, on both PC and phone, whether in tweet-form or using the direct link. [Todd Howard voice] It just works.

That the issue only happens in my PC’s browsers, and in none of my phone’s, would indicate the cause is something on my PC … except it only affects some GIFs and not others, and I can’t imagine what the difference is between those that work and those that don’t.

I know it’s a minor thing overall but it’s weird and annoying so I really want to fix it. Any help in troubleshooting this would be greatly appreciated.