Error found I think 
It was this commit Read metric names from XML file (was filenames) · tribe29/checkmk@f01c463 · GitHub
It changed the finding of names for the metrics from the file name to the XML file.
What is very interesting is the following - at the moment only service without space inside the description are working. Why? The function cannot find an metric for services with spaces as these spaces are replaced inside the XML file and the filename.
On the first look i see no replacing of space with underscore in this commit.