Ok, I believe the mystery is solved: 3.01.1 contained debug versions of Z12 and Z6 for some reason. I've just uploaded the release versions here: https://opserver.de/down/Z12.zip.

Unzip them in your Strategy folder. Make sure that the Z12.dll is now from January 23, not from January 22. This should solve the problem. We'll put the release versions also in the 3.01 setup in the next hours.