I have similar problem, but instead of rejected, my subscriptions are waiting for review for 3 weeks or longer... I can't attach subscription to app, no such option.

Still no any contact to me. But my subscription status changed and now is "Developer Action Needed". What action? Everything is filled in. As I know, i shouldn't submit it manually, but with build. Documentation says "On the right, scroll down to the In-App Purchases and Subscriptions section.", but no such section.

Same for me. This process is definitely broken or unclear.

I created a new one subscription and it started to be visible to submit with app. Do definitely a status "Developer Action Needed" requires something to trigger it to change to ready status. I could delete them and recreate but product id can't be reused anymore. Apple, come on! How could you show only "Developer Action Needed" message without telling us what action?! You order us to create clear apps for users, but your tools are buggy at all.

I've found a solution. I need to delete subscription products with status "Developer Action Needed" and create a new one. This needs changing product id and fixing app for new ids... Apple, fix your process, it's buggy.