Can't get my refresh token anymore?

[PacuFTW]

Plan

Premium

Country

Hungary

Device

ESP8266

My Question or Issue

I've been developing an ESP8266 project for a while now, and until now everythign was fine.

Come today, and the access token can't be refreshed. I went and tried to create a new app, to get a new refresh token, but even that does not seem to work.

I tried getting the refresh tokens this way, but it seem to give me a File Not Found error. What exactly happened to my project, and why can't I acces these anymore?
Any help would be appreciated.