Hi looks like everything is back to normal 
I quickly want to explain, why the cause of this behavior, was not obvious or easy to spot - at least not for me:-(
In my system configuration the Quattro’s inputs are connected and configured:
AC1 = Generator
AC2 = Grid
As I wrote in another Topic, Quattro & BYD V2L - Grid Feed-in Problem
I sometimes have a car with:
V2L connected to AC1.
To prevent the solar battery being charged from the cars battery,
I had to install an assistant: “charge current control” see above pic.
This assistant was set as in the pic above, but with 1 addition:
I also had the option “Disable charger when charge current should be zero” ticked.
What was not obvious, is that this also has an effect on the MPPT’s ,
when ONLY AC2 is connected!!
Luckily Nick & Izak Burger, who seems to have has some insight of the inner workings of the assistant, gave the right hint 
THANK YOU
Cheers and thanks to all participant, for your inputs and help 
Jurgen from Namibia
PS: I never thought about the assistant, causing this - shame on me 