Thunderbolt Native Card/16 I/O not a Playback Engine Option

[js_nyc]

Hello all,
Working with a client- configuration:iMac 2013/Catalina/Thunderbolt Native Card to/from 16 I/O. System was "working" when client re-arranged his PT Aggregate I/O to the 16 I/O. I quoted "working" because even though the Outputs were operable, he could never get the low-latency Inputs to perform properly. He upgraded to PT 2021.12 and enlisted my services. On a remote call, I had him download and install the current HD Drivers, Restart, then reinstall PT 2021.12. Even though it shows up in the System Preferences as a Sound Option, it does not show up as a Playback Engine option in Pro Tools. I then deleted the altered PT Aggregate I/O Audio Device and then set up the HD Thunderbolt Native card. Restart/relaunch with same results. Quit/Restart computer and ran DigiTest on the card. It passed with no known issues. Please let me know if anyone has any other options. Thanks.