Ran the check and got this:
Phase 1 - find and verify superblock... Phase 2 - using internal log - zero log... ERROR: The filesystem has valuable metadata changes in a log which needs to be replayed. Mount the filesystem to replay the log, and unmount it before re-running xfs_repair. If you are unable to mount the filesystem, then use the -L option to destroy the log and attempt a repair. Note that destroying the log may cause corruption -- please attempt a mount of the filesystem before doing this.
I retried to mount Disk 4 by stopping the array in Maintenance mode and restarting the array but Disk 4 still was unmountable.
I assume I should run the Disk check with -L now.