iPhone GPS reminders not working

Hello. I have a problem with the GPS reminders on my iPhone (and also MacBook) Pro. They simply don't work. Whenever I set a location reminder, the alarm is never triggered when I arrive at the location. I have GPS enabled for reminders to ''when using'' (I only have this option or never). MacBook Pro Reminders today asked me to use my location, I therefore enabled but still no reminder triggered. I even tried to enlarge the area where the reminder should be triggered but it didn't help.

Is there some trick to make this work? I'm having this problem in the long run, no GPS reminders actually worked for me yet.