I tried also with the crosstab but to no avail. I do not need column groups or nested row groups.
I can't figure out how to show the summary data on one row only. The closest I got was to show the distinct positions with their count but on different rows. See attached file.
How could I get the summary at one go, maybe the logic would be something like that:
= Join(', ', AllDistinctValues(Fields.Position) + ' - ' + Count(Fields.Position))