Hello,
we had the same problem with an object in R80.20 management server.
We did the following to resolve it.
First run:
psql_client cpm postgres -c "SELECT objid, name, dlesession, cpmitable, subquery1.lockingsessionid, subquery1.operation FROM dleobjectderef_data, (SELECT lockedobjid, lockingsessionid, operation FROM locknonos) subquery1 WHERE subquery1.lockedobjid = objid and not deleted and dlesession >=0;"
to check the locked session & objectid
Then, delete the object from locknonos db-table to release it.
psql_client cpm postgres -c "delete from locknonos where lockedobjid='[objid-from previous command]';"
cpstop;cpstart to restart the services.
And that's it, if you run again the first command you see that the query doesn't return data 🙂