DIYBMS current monitor fault

Hi there,
I connect my new build current monitor, but I have some problems, maybe someone can help me.
When I try to set up the Basic settings, the BMS don’t store it, it is switching back to some standard values (as you can see in the screenshot). Furthermore, I see in the status values row sometimes only 4 values, sometimes also SOC, current and so on.
So I think, the RS485 communication is unstable or wrong. (cable from current monitor to BMS is 50 cm).
Current readings work… (sometimes when I can see the values!)
Someone have a hint, what can be wrong here?

I am using a scope now to check the signal:
Request from BMS looking good and clean, 1.4V AB singal…
But the current monitor answer only sometimes…