Struggling with Flair controling ecobee set point

Ok, first up - this has been working flawlessly for some time, but in the last few weeks something has happened and it's not working right.

Scenario - It's Winter. Yes, this is the Southern Hemisphere where the support doesn't shine. Hasn't been a problem in 3+years...

My set point is 20c. I have 3 pucks, an ecobee 4 and 4 ecobee sensors controlling 13 vents. I have a detailed Flair schedule where usually only half the vents are active. It's all been great..

Scenario: All rooms are under 20c. One is 13c and away. ecobee is in the Kitchen, where it's currently 19c, but Flair is set to 20.5c. Flair updates the ecobee setpoint to 19c, which is just over the average of the active rooms, but under the threshold to actually trigger ecobee call for heat. I set the lowest room to 20c. The ecobee setpoint is now 18.5c which is still above the average of the active rooms, but well under the threshold to get ecobee to call for heat. It continues to grow colder.

I've never noted this behaviour before. The Flair setpoint always seemed to be 'just right'. So what's changed? Well, funny story. ecobee sent me an email saying I can now have eco+ on my controller, so I set it up. It was useless. If I'd researched it, I would never have enabled it. It took me hours to get it to turn off to reenable the Flair changing the setpoint. But since then, things haven't been right.

So right now I have 3 theories I need to resolve:

1. eco+ is messing with the Flair setpoint even though eco+ is 'disabled'
2. Flair changed its algorithm to make the setpoint 'just enough' to trigger ecobee call for heat, and it's too close to the threshold to take effect.
3. Nothing has changed, Flair always made the setpoint 'just enough' but it's only now a problem because it's so fn cold here. Temps vary from -3c to 15c at this time of year.

How to resolve?

If 1) - I'd like to get access to my integration logs and see what setting Flair is sending. Then it becomes an ecobee problem.

if 2) or 3) - The algorithm is broken, please fix. If the average setpoint is 20c, why not send ecobee a request for 20c? It makes no sense.

If anyone can think of a 4), happy to hear it.