Manufacturer Huawei installing its own EMUI 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, Work in Backgroud.
But settings depends on EMUI version.
Check which version of EMUI is installed on your device (It’s specified in the phone settings, in point of information about phone).
Сonfigure your phone according to instruction:
Huawei EMUI 9
Huawei EMUI 8
Huawei EMUI 4
If you have other EMUI version, then try closest versions or contact us by email and we will help.