Upgraded to the Home Pro AC2600 - Now Alexa

I recently purchased a Samsung Home Pro AC2600 to add to my 3-pack Samsung Home Mesh AC1300 system in my home. After about 4 hours of getting all my smart switches recognized by SmartThings, I had my system set with the AC2600 set (as the main) and three hub units (all being AC1300).

When pairing my Alexa skills with the SmartThings hub, and getting all devices synced and recognized, The Alexa app sees all devices in the house. However, when I go to use the Alexa app to control the house, more importantly by voice, Alexa says the SmartThings hub is unresponsive.

I have no issues in the SmartThings App, and all devices are controllable, but there is no response with the Alexa system (though all devices are discovered).

I have disabled the skill, cleared all devices and rediscovered, and did a hard boot… and Alexa says the device(s) are still unresponsive.

Any thoughts?

Side note - there was no issue with the 3 AC1300 mesh units and Alexa earlier in the day. Everything was working fine.