A little extra info to this. Maybe others can confirm?
I think that the latest version of the HxC floppy emulator software (2.1.11.1) makes changes in/corrupts the CFG-file in a way that causes this problem.
If I make a change in the CFG file via the floppy emulator software (for instance tell it to forget the last loaded floppy between boots) to the CFG-file from ZoZo that works then HXC manager stops beeing able to mount disk. The problem persists if I revert the change so the file should be exactly the same.
If I replace the CFG file with the one from ZoZo that works then everything works again - even thou the settings are exactly the same in the HxC emulator software.
Can anybody else confirms this? If so I will make a bug report to the HxC guys.