wbinfo -t shows:
root@ucs-member:~# wbinfo -t checking the trust secret for domain SCHEIN via RPC calls failed wbcCheckTrustCredentials(SCHEIN): error code was NT_STATUS_INVALID_SID (0xc0000078) failed to call wbcCheckTrustCredentials: WBC_ERR_AUTH_ERROR Could not check secret
The SID S-1-18-1 is not in the idmap.ldb of the school replica.
The SID is not found with the filter:
In Bug is a script, with which the missing SID and the user is added.