Switching Newtab icons to "Hover to show" makes the gifs disappear

[MozMatej]

The thumbnails now show the actual pages they're "supposed" to. Disabling and enabling doesn't fix it. I have to switch back to "Always on," then disable and enable to get them back.

[ahal]

This happened sometime around when Whimsy got updated for Australis. The gifs actually load very briefly on hover, but are immediately replaced by the original thumbnails again (sometimes you can see a slight flicker when hovering, it seems to be more noticeable in private browsing for some reason).