Win 8.1 version of a Microsoft app Fix needed

Application name: GPS Navigator Recorder
OS: Win 8
Original developer: Stefano (maybe Salt Lake City before him)
I am only a user and have access to the frontend; no access to files or backend of the app. You yourself can download the app from the Microsoft Store and see what I mean.
I am facing a couple of issues with its' syncing with Onedrive. (Onedrive team assured no issue from their end and it is something with the app.) This app used to work perfectly until a few months ago, on the same phone.

Can you help me fixing this? I don't have any access to the backend or the source of the app. Maybe replicate it, if possible?

Please see I am looking for a low-cost fix, if possible. Ideally, It will be best for the freelancer to understand the issue if he can download the app on his Windows 8 or 8.1 phone.