I have already uploaded a new version 2.14.1 that might improve the situation (but it's still stuck in the Microsoft Store certification process). I am also in contact with Microsoft about how to deal with this background task problem. Reinstalling the app might fix the problem, please make sure to create a database backup before doing so.
Sorry for the troubles!
Edit: 2.14.1 was just approved in the store, please give it a try