i got a tricky one:
I can't set valid breakpoints. Not in Tests, neither in my Java Classes. I searched Stackoverflow and google, but I couldn't find anybody with the same problem.
I'm using STS(x86) and Maven.
Edit: It may seem confusing but I solved it by myself.
I have to go Run-> Skip all Breakpoints (it was set, and I wonder how it was set, because I didn't do it)
There is a menu entry you have discovered for yourself that toggles the skipping of all breakpoints. There is also an icon for this in the "Breakpoints" View, and there may be a hot-key defined as well, all of which you may have triggered by accident.
Take a look at the Run -> Skip All Breakpoints.