I made the mistake of deleting the win phone app from my win 8.1 phone to see if there was an update. Now the app will not download from Microsoft store, at all, just comes up with an error message. Thankful I have my old phone with the app on it, or would be up the creek without a paddle.
Ended up rebooting win 8.1 phone 3 times and it finally downloaded the app, so all is well again.