This was first reported 2 months ago to esri. All our newest Samsung S7s that run the latest version of Collector are now getting the NMEA warning and intermittently failing to get a location fix. Only remedy is to flick out the app to completely close it and reopen. Very frustrating for our Rangers and other field staff.
What is the specific model number for the devices in use?
I recall not being able to reproduce this issue with a galaxy S7. Please provide your current location settings for the android device itself and how long it takes for a location to drop. Also ensure that Android and Collector are up to date. Are your devices using the same carrier(Telus, Optus, Vodafone, etc)?
It got a location. But interestingly I just opened Collector and could not get a location. I had been using the app earlier in the day. I flicked the app out and got the NMEA warning and got a location.