No this is not a Dbvisit error but an Oracle error. (ZD7135)
Looked on Oracle support & found the attached document Doc Id 1954276.1 related to this error.

There is a workaround for this

EM backup report ran from v$rman_backup_job_details for a Physical Standby fails with:

WARNINGS from v$rman_backup_job_details a * ERROR at line 24:
ORA-06550: line 24, column 9: PL/SQL:
ORA-00604: error occurred at recursive SQL level 2 ORA-00904: "SYS"."DBMS_RCVMAN"."NUM2DISPLAYSIZE": invalid identifier
ORA-06550: line 23, column 4: PL/SQL: SQL Statement ignored 


When database is only MOUNTED monitoring credential should have sysdba privilege.

Workaround: Give sysdba privilege to the login user.REFERENCES