Deleted device in HomeKit cannot be rediscovered

I have a Honeywell T10+ Pro thermostat (one of 2) that was working for a short while in HomeKit....until it started saying "updating..." endlessly - and ultimately turning into "not found". After a lot of searching for answers I ultimately deleted it on my iPhone/Home app thinking it would be simple to add it back. WRONG!

Add Accessory doesn't see it. And when I go to the setup menu of the device and follow the instructions (shown below) - it doesn't show a code - it jumps right to "Success- We've successfully linked HomeKit with your thermostat." Of course it doesn't show up in Home. I do NOT want to reset the thermostat as it is set up with a remote sensor and also already linked to their Resideo app.

Any ideas?

Apple® HomeKit® Setup for Honeywell T10

1. Touch Menu icon at the bottom of the T10 home screen.

2. Scroll down and select “Connect Home Kit”.

3. Use the Apple Home App and select “Add Accessory”. Scan the code shown on your thermostat with your phone.

4. Follow the instructions on your phone.