Admin bar turns black on Mobile devices

Hello,

I just found out that one some multi sites that I am running, the admin bar is not displaying correctly. Its just blank (will only see an empty black bar - see what I did there :wink: This only happens on the mobile devices (being responsive) and not when displaying on a desktop Screen.

I can't really tell when this happened, it used to work a while ago. Maybe after the Buddypress update?

Anybody have any ideas?
Cheers,

Ronald