I had same issue. Check if it was the display of map which haven't been downloaded/buffered. Change the display to be spark's camera instead of map, click "+"/"-" at the bottom-right.
I have that issue on certain devices that don't have enough nuts to support GO4... and sometimes on the ones that do. Its a flaky app imho, and highly moody. Perhaps a midol injection...
I have a couple of SanDisk HC-1 32Gb cards which work perfectly fine in my P3S at full 2.7k res, but FRED (my Spark) whines about the speed not being sufficient even at 720p. They do work though, with no fpv issues *except* on certain devices.
And I've yet to find any device that will load the editing software without crashing with either drone. I, like many others, wish dji would separate that stuff and just give us an app that will atleast function reliably on *most* [android based] devices. They're just trying to do too much in a single package when its not necessary imho. I do my edits on a pc or laptop to start with.