I have just filed this bug:
I hope this helps.
Regarding the mumamo issues, I will try to contact the people maintaining
that package, which as far as I know, is outside of emacs.
Please make an Emacs bug report for it as well. Maybe the problem is on
mumamo's side, but maybe it's on Emacs's side (and maybe it's both or
neither, of course).
That is why I figured it would not be something that was necessarily
fixed before the next release.
I'd better try and find out what's the problem soon, so we can decide if
it has to be fixed before 24.4 is released.