How can I add apps to the Open-In menu of the iOS native mail client?

I use the native iOS mail client to access my company email. Everything was working fine -- I was able to open Office docs in the iOS mail client and was able to use the iOS versions of ppt, word, excel and the office mobile app.

However, once I installed the Outlook mail client for iOS, i noticed that i was no longer able to identify ppt, word, excel files or choose to open them with iOS native versions of each of those files even though I have the apps on the iPhone.

I deleted the Outlook client, and reset the phone, but I still don't see ppt, word, excel in the Open-In menu of the native iOS mail client.

How do I get back to where I was before I downloaded the Outlook mail client for iOS?

Really bummed out at the loss of functionality.

Thanks in advance for your help!