Subsequence in New thread blocks Main thread

[GoKu25]

I have a async VI that runs parallel with TS program in a subseq. I'm calling the subsequnce in a New thread from the Main sequence. I also have a DMM subsequence that runs without any problem following that. But If I were to place a break point in any of the steps in DMM subseq, the program no longer runs and the resume and step icons are disabled. The program resumes when I stop the VI  running parallely.  Is this is a problem with the VI?

The same situation does not occur if I call the parallel VI in an action step in main sequence using Start Asynchronous Call node. 

[Norbert_B]

Please post your code instead of a screenshot. Without seeing what you are doing, we can only wildly speculate on what is going on.

One question: Do you use the same VIs in the both threads?