Apple Pay Express Mode with multiple cards and transit passes on public transit

Apple documentation says: Multiple cards, passes, and keys with Express Mode can be active in the Wallet app at the same time.

If the apple devcie is set with a Visa card for express mode, and as well having a valid pass for the transit pay - that as well set as transit card.

When trying to pay on the transit reader, getting a multiple card detected error in the terminal. And then it accepts the emv card. Can you clarify on the intended way of working.

[Re-Titled by Moderator]

Original Title: When riding public transit using Apple Pay express mode set on both the EMV card and a valid transit pass