Thank you so kindly for the tip.
It seems this has happened to some others as well. It is a mystery ...
The work around suggested is here
But I ended up dropping the database set (ReportServer , ReportServeTempDB) and re-create them with the RS config wizard and restoring back ( only ReportServer ) and all was back to normal. I had to bring down the SSRS service and take the rap for outage though.
The DB was indeed in simple recovery mode . when and how the REPLICATION thingy git in is a mystery. I am just guessing without any basis that the DBCC CHECKDB ( allow_Repair_with_data_loss) has done something.
I could not find any guidance on the output message of the DBCC command below:
Warning: The log for database 'ReportServerTempDB' has been rebuilt. Transactional consistency has been lost. The RESTORE chain was broken, and the server no longer has context on the previous log files, so you will need to know what they were. You should run DBCC CHECKDB to validate physical consistency. The database has been put in dbo-only mode. When you are ready to make the database available for use, you will need to reset database options and delete any extra log files. .."
What does it mean delete any extra log files ?