@Littlegolden I checked it, but I only found a problem with account unlink (fixed - v0.1.3). I also installed the clean latest version of Flarum and extension, everything works fine.
I would suggest you check the PHP logs / server configuration. Also check database - login_providers table.
Tested on:
- Flarum 0.1.0-beta.11.1
- PHP 7.2x / 7.3.x
- MySQL: 5.7.x
- Webserver: Apache + Nginx (reverse proxy), PageSpeed, SSL