Thank you for the hints.
However, I was aware that mixing is sometimes risky but I usually succeed in it. It was not the first time I used 1K over 2K but first time with such troubles.
Mixing paint types has some advantages - you may easily remove paint excess and save layer underneath i.e paint with enamel over acrylic.
I am pretty sure that I rushed too much as I wanted to be on time on the local Modeling Contest. Sanded 2K, too much thinner = disaster.