I have noticed that wedge is being counted as a block after the new Roblox Studio Update. It would not be a big deal, however it kinda breaks the SurfaceGui.
It has always been like this, as of right now the only option that I know of is to make a wedge out of parts, and put the SurfaceGui inside of the parts it’s made of.
However, doing this can severely reduce performance, especially on older devices/mobile phones.