Thumbnails no longer animated after uploading vids?

To be clear: I can still see other thumbnails that are animated, even videos I've previously uploaded.

However, every vid I've posted this year has shown still images as thumbnails. It's bizarre to see next to one's that are animated.

To my knowledge, nothing has changed in uploading content. You pick the cover, add the description text, and done.

Is this happening for anyone else? I have the option turned on. And it doesn't seem to matter if I upload from tablet or phone.