2nd order scheme

Yes, you are right. Although the log says differently, somehow the file is not updated.

So the switch does not happen?

The difference, especially in the diffuser behaviour is huge

If it would not affect the results we would all just use first order and not strive the fourth at some point in the future.
But the technical issue here is that the switch to second does not happen. It seems to be a windows related issue and I am on it.

Ok, so the issue is indeed Windows related:
https://github.com/blueCFD/Core/issues/108
The blueCFD guys have to fix it, so we will need a workaround, which they have suggested to me. I will see if it can be implemented.

I am still conviced that to provide a Linux virtual machine or to try the installation under Ubuntu would be a good alternative to a windows porting.
I hope the workaround will work.

Problem solved