We have tried to contact Apple Support (I didn't get a response after more than 3 weeks). Then we tried to ask about the issue in the review thread. I'm not sure the reviewer even read what we have written, because their response was a pure "read the docs" answer.
Issue resolved so far, see post below. It's unbelievable that such a simple issue took a few weeks for us.
Topic:
App Store Distribution & Marketing
SubTopic:
App Review
Tags: