Just had a similar problem with my Samsung S6. Map stopped being shown in Samsung Health either walking or hiking, having previously worked well for several months. I checked the Settings for the app and turned on "Location information". That seemed to allow the map to be displayed but my route was still not being tracked. I have now used Stettings - Device Maintenance. It was showing 75%. After optimising it is now at 100% and route tracking seems to be working again. Hope this helps someone.
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