I also found a bug. Yeah!. 
Sadly its only a minor one. 
One cant see the specators on a demoboard. In games there is no problem
It only happens in Iceweasel (so presumably also in Firefox, but i dont know)
In Chromium all was fine.
This issue may or may not be fixed now… i haven’t seen it myself since the last round of patches, and i touched some stuff that might have fixed this. Let me know if you see it again