Hi all,
Fortunately I solved this problem by changing Slurm version from 22.05.9 to 23.11.10.
With Slurm 23.11.10, after stopping the primary slurmctld and slurmdbd, when I submit a job with sbatch while backup slurmctld and slurmdbd are running, the job becomes scheduled and runs.
I don't know why, but this is OK.

Thanks,
Hiro