I'm having a similar issue. We have a published app and we're just trying to add a new subscription to an existing subscription group that has only 3 subscriptions in it. On the App Store Connect page, it says "An error has occurred. Try again later."
We've been trying this for the past 12 hours many times and keep getting the same error. So we tried logging with a different apple account and it failed again. Then we tried adding a new subscription to another app's subscription group and it failed again.
This is most definitely an error in the App Store Connect website or API.
taufiqito90
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