Solution
This is an expected behavior, when Rendezvous step is created, are defined a constant number of sockets that are synchronized at the starting step. The same number of sockets is waited at the end of these tests.
The operation that you want to perform can be done using the Batch process mode and the Batch Synchronization Step . Here, even if you start the synchronization with six sockets and you terminate the execution of one of them, the Batch Synchronization Step will wait only for the sockets that are still in execution.
You can find a Batch Synchronization Step example in:
<Users>\Public\Documents\National Instruments\TestStand 2017 (32-bit)\Examples\Built-In Step Types\Synchronization Step Types