App is stuck installing on my iPhone, how do I fix it?
You mentioned this device was upgraded from iOS 9. In my experience an iPhone that has been upgraded from previous OS that has not had a full restore on it in years is prone to reliability issues like this.

I typically do a restore at least one time per year (I experiment a lot and "cruft up" my phone).

Its a pain however its probably time for a full restore...  The phone will run like new afterwords.



Note: Back up all data before you preform this action, otherwise all data will be lost.