I don't know if anyone else has seen this, but I have a project that I started working on a few days ago, and just this morning, I lost the ability to set breakpoints in it.
It is a datafield project, and today I can no longer set breakpoints, that is, the red dot appears, and as soon as I start running the application, the breakpoints all change to empty circles with "Unverified Breakpoint" appearing when I mouse hover over them. In other languages this is a problem with the directory that the source is in, but I haven't changed anything. In any case that isn't something that you can configure in the launch config for Monkey C.