Mobile Google Maps' setting for receiving location share notifications
First of all try clearing the cache of Google Maps application.

Secondly try changing the appropriate notification switch using the following steps:


Open the Google Maps application
Tap Menu Menu, go to  Settings >> Notifications >> People and places >> location sharing (get updates when people share with you on maps)
Next to the notification (location sharing), turn on the switch (if enabled already, turn the slider off and then on).