I believe the issue is probably that you are missing some of the requirements for in-app intent handling. According to this WWDC session, these are the requirements:
Add support for multiple windows using the UIScene lifecycle
List the supported intents in your Info.plist
Support the application delegate intent handler call (which you have already done)
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I think I've found the answer here. It looks like we need to:
Support multiple windows using the UIScene lifecycle
List the supported intents in your Info.plist
Support the application delegate handler call (which we already did)
I'll give it a shot and let you know how it goes
I'm running into the same issue and I'm wondering if it has something to do with the target OS of my app. I'm currently targeting iOS 12. How about you?