I set up a new project just to make sure something else wasn’t interfering, and it turns out it kind of is, but I still can’t get it to work properly anyway. I couldn’t find any flipbook nodes other than the node to create a flipbook, so I used regular texture samples, and I also used a sprite of Simon Belmont as the artist doesn’t want their sprites public. The set up I used was the only way I could get the sprite to not be any of the following: invisible, black border, nothing changed.
The problem in the new project is only part of one boot is the new green (test) color, the real project nothing changes at all.
This is as close (I think) I could get it from your instructions as I couldn’t find any way of using a flipbook instead of a texture sample. Again this is mostly if not all down to my lack of experience with materials. For some reason I thought I’d be able to get away with never using the material editor, and I can honestly say I was as wrong as you could get.