I’m not sure which devices and OSs are impacted, but the most recent updates for the Guthook app are buggy and cause the app to be useless for the sorts of purposes PCT thru hikers use it for. I updated to Guthook version 10 a few days ago and still cannot get the app to work. Here is the most recent email with Tech Support at Atlas Guides (the company that developed this app).
I would recommend that hikers NOT update this app (and turn off automatic updates) until you are in a place for a couple of days with reliable WiFi and can fix any problems that arise.
I put out a sign alerting hikers of the problem.
Update: Once I was in a place with WiFi, I uninstalled and reinstalled the newest Guthook app, as instructed, and it returned to working as expected.