This is a common occurrence. The machines are perfectly capable of undertaking this transaction, but Germans are VERY risk averse and regard foreign card transactions with great suspicion.
I explain a bit here (and another German gets quite chippy in his responses), but it’s mostly a cultural thing - Germans hate being in debt so credit cards have never really taken off, and a “card culture” never took root.
But it also has its origin in the reluctance of traders to accept ANY credit cards - because, unlike Giro/EC karte, they are charged a (small) percentage of the bill for receiving the money - the horror ! This is unacceptable to German traders, when they could have 100% of the cash. Trying to convince them that, perhaps, someone will potentially spend more money with them if they accepted cards - particularly if they didn’t happen to be carrying the cash around with them. Even shops and restaurants who do (theoretically) accept Visa/MC will try and pressurise you into paying cash. Or claim that they only accept “German” credit cards. There is also a fear of fraud from foreigners. This drives quite a few to not want to accept a card from abroad, even though they theoretically could.