Fixed in 12.3.7 HF1 - An issue has been solved in which AS/400 Job aborted because the Library was already in the list. SBMJOB issued without INLLIBL(*JOBD) OUTQ(*JOBD).
Delete the TMP file and recreate it new.
First, stop the agent. Then, delete the TMP File out of the library with the command: "DLTF FILE(UC4/TMP)" and create it new: "CRTPF FILE(UC4/TMP) RCDLEN(256) MAXMBRS(*NOMAX) SIZE(*NOMAX)". Then restart the agent and try it again.