Messaging extension does not work when issuing a message to an individual for the first time on iOS
Steps to reproduce:
1) Using iPhone (iPad not tested), create a new chat and select a user that you've never previously chatted with.
2) Use an app that supports messaging extensions to perform a messaging extension search query.
Result: No results are returned.
This appears to be a bug in the Teams mobile client on iOS as the bot does not receive any requests when executing the outlined steps.