The problem comes from the way Request Manager proceeds to recover existing variable objects in One Automation. The UC4 call API that is used by Request Manager, recovers and lists all VARA Objects, and does not take in account the privileges of the AE user;
Potentially VARA objects, the user is not authorized to access, may be present in the list. Here in this particular case, the search in Globalstore tries to read VARA Objects which are located in <No Folder>, but the AE User not have the privilege 'Access to <No Folder> granted.
Problem was detected in the following environment : UC4 12.3 with Oracle 12c - RM 3.51 with Oracle 19c. But this is transparent for this kind of issue because the problem comes from missing user privileges in AE.
To avoid this problem, the AE user used in the Connector Configuration in NEXUS, should have the following Grants:
-- Privilege 'Access to <No Folder>'