Problem precisely described on Oracle website https://support.oracle.com/knowledge/Middleware/2338182_1.html with its solution doesn’t solve it in specific case.
I have created RCU schemas with OSB12C prefix. There were some other issues and I had to reinstall it.
I was trying to reinstall domain on the same RCU set but it failed. This forced me to re-create RCU, everything the same but Prefix was modified from OSB12C to OSB12, to exclude any kind of conflicts.
I moved back to OFM installer and tried to install new OSB domain on this new RCU setup but it failed every time when it was trying to pass OPSS Processing step.
It failed exactly with below details:

Error: CFGFWK-64254: Error occurred in "OPSS Processing" phase execution.

Exception:

oracle.security.opss.tools.lifecycle.LifecycleException: Error during configuring DB security store. Exception oracle.security.opss.tools.lifecycle.LifecycleException: JPS-00260: Database access error. SQL state: 42000, error code: 942..

com.oracle.cie.domain.security.external.ConfigSecurityException: oracle.security.opss.tools.lifecycle.LifecycleException: Error during configuring DB security store. Exception oracle.security.opss.tools.lifecycle.LifecycleException: JPS-00260: Database access error. SQL state: 42000, error code: 942..
at oracle.security.opss.tools.lifecycle.cie.OpssSecurityConfiguration.initializeSubsystem(OpssSecurityConfiguration.java:191)
at com.oracle.cie.domain.progress.domain.generation.OPSSProcessingPhase.initialize(OPSSProcessingPhase.java:211)
at com.oracle.cie.domain.progress.domain.generation.OPSSProcessingPhase.processOPSS(OPSSProcessingPhase.java:154)
at com.oracle.cie.domain.progress.domain.generation.OPSSProcessingPhase.execute(OPSSProcessingPhase.java:54)
at com.oracle.cie.domain.progress.AbstractProgressGenerator.run(AbstractProgressGenerator.java:94)
at java.lang.Thread.run(Thread.java:748)
Caused by: oracle.security.opss.tools.lifecycle.LifecycleException: Error during configuring DB security store. Exception oracle.security.opss.tools.lifecycle.LifecycleException: JPS-00260: Database access error. SQL state: 42000, error code: 942..
at oracle.security.opss.tools.lifecycle.OpssDomainConfigImpl.configureDBSecurityStore(OpssDomainConfigImpl.java:616)
at oracle.security.opss.tools.lifecycle.OpssDomainConfigImpl.configureSubsystem(OpssDomainConfigImpl.java:489)
at oracle.security.opss.tools.lifecycle.OpssDomainConfigImpl.initializeSubsystem(OpssDomainConfigImpl.java:269)
at oracle.security.opss.tools.lifecycle.cie.OpssSecurityConfiguration.initializeSubsystem(OpssSecurityConfiguration.java:188)
… 5 more
Caused by: oracle.security.opss.tools.lifecycle.LifecycleException: JPS-00260: Database access error. SQL state: 42000, error code: 942.

It looks like OFM installer has problems when SCHEMA OWNER prefix ends with digits (in my second attempt case it was OSB12) and can’t read data from RCU setup and transfer it to configuration. When it is with letters then it is fine.

The other thing is the fact it is not so easy to delete all the stuff to reinstall RCU with the same prefix what in final can result with multiple duplicated schemas in DB. To remove it, it is enough to run below SQL using account with SYSDBA role. Please remember to replace YOUR_SCHEMA_OWNER_PREFIX_123 with your value.

drop user "YOUR_SCHEMA_OWNER_PREFIX_123_IAU" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_IAU_APPEND" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_IAU_VIEWER" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_MDS" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_OPSS" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_SOAINFRA" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_STB" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_UMS" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_WLS" CASCADE;
drop user "YOUR_SCHEMA_OWNER_PREFIX_123_WLS_RUNTIME" CASCADE;

DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_STB;
DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_WLS;
DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_MDS;
DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_IAS_TEMP;
DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_IAS_UMS;
DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_IAU;
DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_SOAINFRA;
DROP tablespace YOUR_SCHEMA_OWNER_PREFIX_123_IAS_OPSS;

DELETE FROM SYSTEM.SCHEMA_VERSION_REGISTRY$ WHERE MRC_NAME='YOUR_SCHEMA_OWNER_PREFIX_123';