I've been watching this for a while now to be sure, but now it has been confirmed, when the option "Show media on the lock screen" (freely translated from german) is activated, the contactless payment process via Curve works only for the first step, tap on the terminal and confirm with your fingerprint, then tap again, but in the second step the terminal displays "Follow the instructions on your phone" and after several times of trying to tap again the terminal displays "Please put the card in or use another card". The payment also doesn't go through when the phone will be unlocked then.
Without the media player option enabled, every payment works flawless.
Actually no problem, I can leave the media player on lock screen option disabled, as it's more a "nice to have" option for me, but I really would like to know about the correlations, is it a bug or is it possibly for safety reasons?