ORA-21561: OID generation failed

Oracle 19.24 version - 4 instance RAC on OEL7

many Linux servers connects to our database for data load. Recently, we have been getting the error, ORA-21561(on the client side), intermittently. We talked with network folks and they checked DNS and did not find any issue with resolution. the client correctly includes its fully qualified and short names.

We do use scan address instead of vip in our connection string. We have not make any recent changes on the db server or on the client side.

What else should we check and can we run a trace?

if we can run some trace, please let me know how to start the trace, etc.