Our cloud is not running wsproxy at the moment, and we're still investigating why. We expect it to be resolved tomorrow. It's still a bit early for the feature to be stable (the changelog does say it's still in beta).
To be sure that WebADM picks up the setting properly, can you check the values for OpenOTP's Mobile Token URL in the Applications tab? They should start with
https://cloud.rcdevs.com .
If you've been using push notifications without a reverse proxy for years, as you write, and since cloud_wsproxy is a months-old feature, I can only assume push notifications were working because your smartphones were on your local wifi and could answer to WebADM directly. If that's the case, you can go back to not using the wsproxy feature.