If Michael's good suggestion doesn't fix it....
Maybe delete the MapRun6 App from the iPhone SE.
Reboot the phone.
Reinstall MapRun6 and note particularly when you go to use it the first time (ie "Go to Start" or "Events Near Me"), you should be prompted to OK it using your location. Be sure to answer "While Using".
If this doesn't fix it - Please report back on which of the above steps seemed to fail.
You also try MapRun version 7.
https://apps.apple.com/au/app/maprun/id1634949963 - Similar process to MapRun6, you will be prompted to allow use of your location when locations are first needed ("Events Near Me"/"Select Event" or "Go to Start").
If none of this works please let us know what version of iOS is on the iPhone SE. (I note that I do use an iPhone SE for testing MapRun6, and haven't had this issue),
Peter