For correct work of application:
1) In “Settings ⟶ Battery” turn OFF “Power saving mode” and “Ultra power saving”.
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2) In “Settings ⟶ Battery ⟶ App launch” turn OFF option “Manage automatically” then click on Prof Reminder and turn ON options “Autostart”, “Work in background” and “Indirect start”.
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3) In “Settings ⟶ Apps ⟶ Permissions ⟶ ⋮ ⟶ Special access ⟶ Battery optimization ⟶ All apps ⟶ Prof Reminder” select “Don’t allow”.