Time Machine crashes when preparing new external drive

I purchased a Thunderbay4 (Thunderbolt 2) 16 TB drive to replace an older disk. I have certified the disks with SoftRAID, initialized them, and created a new volume using RAID 5 and HFS+ file system. When I go to Time Machine, I select the new volume, and tell Time Machine to replace the old disk. At that point, it starts to prepare the new volume. The bouncy progress bar goes back and forth a few times, then freezes. The volume is immediately unmounted, and I have to force quit System Preferences. While Disk Utility sees the new volume, it can't mount it. The only way I can mount the volume is to re-initialize the disks and create a new volume. The process then repeats when I try to use Time Machine. Below is a screen shot of the crashed Time Machine.

I'm running Big Sur 11.6 on an iMac (Retina 5K, 27-inch, 2019, with 40GB of RAM.

Does anybody have any solutions?