Hi FrankH,
I experienced the same symptoms here in Finland later in the autumm. I think it is right, that the regen comes alive when the battery has got its temprature set up right. From my opinion its quite logic and safe system when thinking about the battery life in general.
If there is no problems riding in warmer enviroment and the throttle is working ok, then i think its about the coldness. You could try to power the bike up for 2, 5 or 10 minutes and see if the battery heats a bit before the ride.
Blocking of the "air intake" is also a smart idea in colder weathers. I did not have the time to test that before the bike was sold. Anyhow general feelings with the + was very positive this season, the regen and double capasity batteries made riding times much comfortable. It customised my personal riding style quite radically. I learned to ride more smoothly and always trying to regen when there is a possibility (:
The plus has almost no chainslap and that i could see from the status of the chain. First chain tightening had to be done at 1500km and just basic cleaning and lubricating during that time.
Anyway the + has smart features what i have noticed during 3000km driving in this year.
When the engine fan goes on (+65C) the bike is not giving the same amount of power when the engine is below 65. Its really a small differece, but i noticed it when a customer was giving feedback from a longer ride and i made the same test. Anyhow the system limits power when the engine starts to heat up over those parameter what are mentioned in the owners manual and the really high readings usually give you a note to dash hot engine / cutback etc.
I usually drive below 6 kw output just to geep the engine temprature low (fan off) and pedestrians confused when i stop to a trafic light stealthy. Feels like the bike rewards you from a smart riding style. I also dont usually ride faster than 90km/h i think it the best driving speed in the highway when trying to maintain smart range.
Thing what i would add to the + would be the "windscreen" and maybe the central stand for makeing the wash and maintenance more easy. With a deacent price also. Windscreen would give the bike a bit more aerodynamics and you could place your head behind it if maintaining +100km/h speeds for a longer time. Its sometimes a struggle to keep yourself behind the bar when having very windy conditions. The seat could maybe a bit more softer also, but thats a taste issue.
In that detail view what you mentioned i have also used it for curiosity about the regen power and things like that. Sometimes i monitor the charging trough that detail view also.
Also noticed that the bike is very spesific with the range estimation. For example when the battery is dropping under 10 procent the bike does not give even half of its original power (2-4kw), just because it wants to promise you estimated range.
Safe riding!