It went through with another account and a different topic (instead of Services -> Wallet, I used Design -> General). https://developer.apple.com/forums/thread/795871

I've managed to post it with different username and under the different category (Design / General, instead of Wallet). Not sure what happened.

I've managed to post it at the end with a different account and by setting a different category. I'm not sure why Tools/Wallet didn't work.