Error occured: XXXXXX API not found!

[aaronjrich]

I have an API that works fine in the Azure Gateway but when trying to Export the API for promotion, it gives this error on a couple of our endpoints. We think we traced it down to endpoints that indicate they're returning a string. One endpoint is returning a FileStreamResult (returns a File(...)), the other a string; each cannot be exported and gives that error. I've tried V2 and OpenApi 3.0.1 swagger formats but that didn't help here. Any help with this issue would be appreciated.