My browser / operating system: ChromeOS 12607.82.0, Chrome 79.0.3945.123, Flash 32.0 (release 0)

So I was trying to make a clock (I found a workaround for my specific case) and I found that a single-line sprite wasn't showing up. (Second hand, minute hand, etc.). When a added a square, it showed up again. I deleted the square (leaving only a line) and it hid again. I tried SO MANY things to get it to show, none of them worked. Is this happening to anyone else? Or is it just my computer messing up?

This is probably obvious, but a single-line sprite is a sprite made up of a single line.

It's happened to others, including griffpatch. Horizontal line costume does not appear on stage