@jon I also had a weird experience last year. I was on a train from Austria to Italy, passing through Slovenia.
As I was heading out a Roma woman was being controlled by two policemen, one from Italy other from Germany. She spoke in German with the German officer, and showed her papers on the phone. The German officer told she was good to go. But the Italian one told she need a physical document to enter Italy. So she had to leave the train.
What I found weird is that:
She was the only one checked, Roma, BIPoC.
Two policemen, from different countries, has different opinions.