Unable to set or edit watch variables, and unable to use Evaluate Expression in main thread

I’m unable to add, or evaluate any watch variables. Evaluate Expression also does nothing when I try to execute it. If you look at the screen below, if I try to add a new watch variable, it just outputs a blank line and doesn't let me edit them (see green glasses). If I switch off of main thread I'm able to set watch variables properly and they stick around when I swap back to main, however it just hangs on "Collecting data..." forever (see params).

It seems to be specific to a single project, as a new/different one works fine. Any idea's on whats happening?