Minor bug when making layered font

I’m making a big family of layered fonts. After adding twenty-second master, I get the incompatibility mark even thou I didn’t have it while making all of the previous styles (and, of course, all of them are incompatible).
I can’t yet upload images so here are some links:
21 masters: http://i.imgur.com/Zy93kct.png?1
22 masters: http://i.imgur.com/vYPXCVH.png?1

And bdw it would be great to have some visual distinction in toolbar icons.
Maybe something like in the Font Info window?

could you send me the .glyphs file? (to support [at] this domain) Maybe only one glyphs?

Actually problem disappeared after adding another master. So it must’ve been a fluke.