No, I doubt you’ve made any mistake. Webflow Memberships is in Beta and it definitely has it’s issues at times.
For example, just recently invitation emails were not being delivered and their users API was silently failing.
It’s not ready for a stable, live site yet. But I’m sure it will be once it’s out of Beta.
In the mean-time, to get past your issue I’d recommend reaching out to Webflow Support. That’ll be the quickest way to get someone to review it.
Secondarily, you can signup to the Memberships Beta forum (it’s separate from this main forum) and post it there as well. But… your turn-around time on an answer will most likely be slower.