We are facing below lock errors with queue processors and though we see the broken item with below error in admin studio. We could see the case processed and moved to resolved state. 

Cannot obtain a lock on instance " ", as Requestor "B--------A" already has the lock.

below is queue processor configuration.

1. In flow we included the run in background shape and passing queue processor details and lock using property .pzinskey.

2. In the queue processor activity. We just have call resume flow step and log message step.

This issue is not occurring for the all the cases processed.