The first thing I would try is checking if iFly GPS, the App Store, or iOS itself have any updates available and installing those.
Next I'd check the Location permission in iOS as per https://support.apple.com/en-us/HT207092
If those don't do it, send us a Bug Report by tapping Menu -> About -> Send Bug Report -> Select Log, and choosing a log file that matches a flight where this happened. It'll attach the log to an email in your client, just type in the top of the message a quick explaination of your issue so we know where to look, and hit Send. Then we can dig in deeper and see what's going on.
Thanks