I find that I cannot break in a debug session until the debugger has stopped at a breakpoint. If I try to break a non-stopped process, one of the sessions stays active and has to be KILLed. Often the package I'm debugging stays locked and we have to bounce the database (easiest solution) to right things.

Another symptom I sometimes see if I break a process is that the debugger loses all of my breakpoints and the process runs to completion despite stepping or breakpoints.

My suggestion to you is to try not to break out of a debug process from the client until a breakpoint is reached. Having your DBA kill the session at the DB level also works.

FYI, when using the debugger you have two processes running, the program you're testing and the process that is stepping through it.