zone-backup error

I have 25 zones in the knot, and I want to make a backup for all of them. I executed command /home/gtld/knot331/sbin/knotc -c /home/gtld/instances/in/etc/knot.conf zone-backup +nozonefile +notimers +backupdir /home/gtld/instances/in/backup/202311061004, but only 24 zones were backed up in the log，only the top zone is missing

...
2023-11-06T10:05:04+0800 warning: [xn--czr694b.] private keys from PKCS #11 aren't subject of backup/restore
2023-11-06T10:05:04+0800 info: [xn--czr694b.] zone backed up to '/home/gtld/instances/in/backup/202311061004'
...

When I run the command again, "error: (operation failed for some zones)" is displayed, and have error in the log

2023-11-06T10:22:15+0800 info: control, received command 'zone-backup'
2023-11-06T10:22:15+0800 warning: [top.] backup or restore already in progress, skipping zone
2023-11-06T10:22:15+0800 error: control, error (operation failed for some zones)

This may be related to the large amount of data in my ZONE and the frequent updates. Is there any solution?