Update September 18th, 2020 (Solved for my use-case):
I realize this may not be helpful for some people, but I was able to figure out the problem at least for my team and hope this can assist anyone else with a similar enough situation. My team and I work on a very large codebase and I only started in my role almost a year ago, so there's a lot of stuff in our codebase that I don't have direct experience with. This also includes some third-party vendors' frameworks that exist in our codebase. Most of these decisions and dependencies were made before I joined the team.
With that said, I made a new Xcode project using 11.6 (the last successful version I used for distributing our app to the AppStore) and used the same Bundle ID and Team combination for it. I tested that I could upload the sample "Hello World" application which was successful. I then started introducing things little by little to isolate the issue and found what the culprit was for us.
For us, it was one of the third-party pre-built binaries that was provided to us which was causing the rejection. Submitting a build without that framework resulted in a successful upload and processing, but including it resulted in the error you see at the title of this post. We plan to reach out to that vendor next week to see what we can do about getting this resolved so we can go back to including Bitcode in our releases.
I hope this is helpful to others in similar situations. I would recommend uploading builds to the AppStore with Bitcode enabled and only providing a small subset of your dependencies until you find the issue. Again, this may not be helpful for everyone, but I hope it's helpful to someone. I can only conclude that rules were changed on Apple's side after the September event and that our vendor's pre-built binary has assembly or something of the sort within it. Good luck to you all and I hope you find resolution soon.
tl;dr
It was a problem with one of our third-party vendor's frameworks and we're going to ask them to investigate this.
Steps to find resolution above.
Topic:
App Store Distribution & Marketing
SubTopic:
App Store Connect
Tags: