Manufacturer Xiaomi installing its own MIUI shell on phones.
It is stand out by very aggressive power-saving enabled by default, which does not allow apps to work normally in the background (while screen is turned off or locked).
For correct work of Prof Reminder it’s required to disable Power-saving and enable Autostart.
But settings depends on MIUI version.
Check which version of MIUI is installed on your device (It’s specified in the phone settings, in point of information about phone).
For example on this screenshot – MIUI 9.
Screenshot
Сonfigure your phone according to instruction:
Xiaomi MIUI 11
Xiaomi MIUI 10
Xiaomi MIUI 9
Xiaomi MIUI 8
Xiaomi MIUI 4
If you have other MIUI version, then try closest versions or contact us by email and we will help.