I had a stack of 3 CLs which were all CR +2. The final CL in the stack was bad, and causing PreCQ failures.

I marked that CL as Verified -1, but the PreCQ continued to pick up that CL in additional to the rest of the stack, causing all of them to fail the PreCQ.

I believe the PreCQ Launcher to not submit CLs that have Verified -1 set.