LaCie Desktop Manager can't see drive: Late 2015 27" 5K iMac

I have the LaCie 2Big v2 Thunderbolt drive (running 2x3TB drives as RAID1).

This worked well on my Mac Mini (late 2012) that I just upgraded to the late 2015 27" 5K iMac. The Mac Mini was running OSX 10.11.1, as is the new 2015 iMac 5K.

On the old Mac Mini, with 10.11.1, I could use the LaCie desktop manager (v 2.3.0) to see the drive status, etc.

When I migrated my system over to the 2015 5K iMac, the LaCie drive mounts and is properly recognized by Finder, as well as disk utility, but the LaCie Desktop Manager insists it can't see any attached LaCie devices.

I found on the LaCie website v 2.7.3 and installed it to no avail. I've deleted the kext, app and preferences using the app's own uninstall function, booted and rebooted, and the LaCie manager still doesn't see the drive. The drive seems fine under Finder, etc.

I have reconnected the drive to the old Mac Mini and the LaCie Desktop Manager sees it properly (again, both systems are on 10.11.1).

Here's what I see on the late 2015 27" 5K iMac:

Suggestions?