The system somehow blocks the HSBC card (and maybe the amex card for @ExpatExp also) from buying Uber cash 99% of the time. The card is then secretly flagged/restricted within Uber's backend system. The only way to resolve this and use the HSBC card to buy Uber cash is to get the right support person / escalation team via chat to unrestrict the card. Most of the time this is difficult because their support is clueless on the issue itself or doesn't know who to escalate to unrestrict the card. I have luck with just keep on pressing them on the chat to unrestrict the card and then I can use the card to buy Uber cash or a regular Uber ride.

If the HSBC card is restricted, then I cannot use it to pay for rides, ubereats, or buy Uber cash. While other cards like amex works fine within the same wallet. I've got $40 bucks to go to get back before end of the year then this card is going on the cancellation list.