Yes. I had modified sssd.conf on the server in pursuit of the solution to proposed change and that is what caused this issue. I reverted the config and authentication/lookups are now working as expected. I'd forgotten that I made that change and since clients with in-tact caches were still working the impact wasn't evident until I configured a new client and enough time had passed that I didn't make the connection. Lesson learned. Revisiting the logs, I see it was the "Failed to split fully qualified name." that led you to this conclusion.
I'm tremendously grateful for your help!