It seems that my app is still functioning OK in production even though it is no longer listed under Manage Apps/Connected Apps. Should it be listed there? The problem I'm having is that my iOS app requires a re-login on every app launch with Sandbox, which makes testing cumbersome, but does not require this with production, and I can't find any config difference between the orgs that would cause this to happen.
1 Answer
This is similar to the question I answered here. The Connected app - client id and client secret can be from any org and it does not matter if you're not seeing that connected app in your org. This thread may also help understand this better.
As for the other part of your question
The problem I'm having is that my iOS app requires a re-login on every app launch with Sandbox, which makes testing cumbersome, but does not require this with production
That's unusual. You can definitely create another Connected app in your Sandbox to see if this resolves the issue.