MP Explorer Visa at unmanned kiosks:
Success at LHR topping up Oyster, no pin requested, £20 transaction
Fail: SNCB in Belgium ("VISA technical failure" message)

Citi Aadvantage MC:
Success at SNCB where the MP failed. Asked for pin, accepted cash advance pin, < €4 transation.

Wells Fargo debit Visa, failed at SNCB above as well but worked as expected at an ATM with an EMV-only terminal.