Are dropdown menus showing up blank in Chrome or Firefox?
Do you have multiple monitors?
Have you disabled all your extensions?
Went into incognito mode just to make sure?
Tried a different theme?
Have you reset your profile (using settings->advanced->reset profile)?
Still not working?
You might be using XMonad, a tiling window manager. There’s some bug going around, that’s supposedly have been fixed in the github repo. Slowly it’s making way to release packages. If you run ‘xprop -root -remove _NET_WORKAREA’ it magically fixes the issue, but periodically it will come back. You can read the details about the issue here.
This issue probably won’t affect 99% of computer users out there, but just in case you’re pulling your hair out trying to figure out what gives here’s a solution for you. If you’re interested in learning more about the issue, click here.