Thanks for using Cloudera Community. Based on the Post, Your Team wish to assign a Region (Which isn't assigned to any RegionServer) without any HBase Restart.
We wish to confirm whether your Team tried using the following approaches:
HBCK2 Assign as documented via . The Command requires the Region ID as argument & returns a PID, which can be viewed via HMaster UI "Locks & Procedures" or "list_procedures" via HBase Shell for Success/Failure.
Within HBase Shell, There are "assigns" Or "move" Command allowing Destination Region Server to be specified as well.
Your Team may have tried the above Command yet the Outcome of the above Command would confirm if there is any Underlying concerns with the Region, which requires additional intervention like HBase Service Restart (Or, HMaster Restart which should spawn an Assignment Manager Thread afresh).
Kindly let us know if the Post was Helpful for your Team. If Yes, Please mark the Post as Solved. If No, Do share the Outcome of the Command shared in our Post. Accordingly, We shall review & get back to you.