Cannot get GIFs to process in Image Block

I've tried uploading several versions of a gif file into an image block. I've tried the following things:
file size is less than 5MB; filename has required restrictions. Tried aspect ratios is 320x180 and 640x360. All pictures within GIFs have same aspect ratio. GIF files play fine on Firefox web browser. Removed cross-fades within video editor.

I haven't been able to find out how much space my website currently holds but I manage another sqsp site with the same credentials that has FAR MORE content so I don't think that's it.

What am I missing?

I just uploaded a random gif from the web to my test site. Uploaded OK and displayed fine.

Have you tried another gif file to see if it's gifs in general you are having problems with? Or the issue is just with the one you are trying to upload?