This appears to be resolved in Mosaic 22.2.3.1, please retry in this version or later. If it's not resolved, please raise a new case online and reference the title of this article.
After bulk assigning requests, the system creates a lock for the person assigning against all the workflow steps associated with these requests. They can only be cleared through the Lock Manager.
The workflow does not lock where:
The request is assigned one by one from the current work (using 'update assignment').
If a case note alert or workflow is bulk assigned (it only impacts requests).
The lock must be manually cleared or is cleared when the assigning worker logs out.