Yes, I've been seeing the same error as well. I looked into it and, as far as I can tell, it's a problem on the Resideo server end. The app handles it and moves on as expected, so I'm not very concerned about it. I'll continue to keep an eye on it.
Thank you @WindowWasher , for the fast reply.
Hello, Everybody,
Today I stumbled upon an anomaly, as follows:
If I set Heat- and Cool Setpoints in one Thermostat call, only the Cool Setpoint is actually changed.
For testing purposes, I created this app:
... and this is the log:
After this, the Thermostat Setpoints are at 70/78, not at 68/78 as expected.
After separating the Setpoint calls
the log shows
and both settings are changed in 80% of the calls.
Any Ideas?
Actually, it's a bug. 
I've seen this happen on my own thermostat, but only during cooling season, when I adjust the cooling setpoint. It hasn't been a high priority, as no one else reported it. So, I just took a look at it a couple of times and didn't see anything obvious. It seems to be a race condition. Thanks for the test app and logs. I'll look into this more thoroughly now that someone else is seeing it.
Yeah, it's getting cold outside and the bugs start crawling in... 
Hmmmmmmmmmm...
Good Morning, Everybody,
This morning I updated my hub to 2.5.2.128, and - the warnings are gone, everything runs as expected.
I ran the test:
and this was the result:
So for now, problem solved. I'll keep an eye on it, though.
Thank you, Tim, for your fast response. Awesome, as always...
Well, to be honest, I didn't do anything. I was planning to look at this today, which I will still do. Interesting that the latest hub update changed the behavior. Thx for posting so I don't go crazy trying to reproduce the problem.