Subliminal can get in a state where apps won't run

Question

OSX 10.9.3
xCode 5.1.1
Instruments 5.1.1
IO simulator 7.1

I am in my "Integration Tests" scheme and I launch my tests using profile. I can do this multiple times, but eventually (almost always when there is a test error). The tests won't launch. I get 2 distinct failure cases:

In the first case, the login screen of my app appears in the simulator and Instrument's says the script is running, but nothing displays in the trace log.

The second case is similar to the first case except The trace log says "Test are starting up ..." but they never do.

Sometimes, stopping Instruments and running the tests again via profile causes them to run again.
Sometimes, I have to also kill the IOS simulator.
Sometimes, I have to also restart xCode.
Sometimes, I have to reboot.

It may take up to 10 attempts to get the tests to run again.

When I look at the main thread when the tests won't run, it has been sent a sigstop.

Is there deterministic way to get the tests to start running again when the system gets into this state?
Does anybody know what causes this?

(I read the known issues post "Tests occasionally fail to launch when using Xcode 5.x and/or the 6.1 Simulator and/or Mavericks" - but the proposed workaround has never worked for me)