I have been experiencing the same problem since yesterday.
I was using my Emlid Reach RS2 yesterday at 11pm and it was working fine. Then when I tried to use it again at 1pm it could not hold a fix. It just keeps going back and forth between Single and Fix. It also was only getting about 26-30 satellites whereas normally I get about 35. I just tried it again this morning and it did hold a fix for a minute and then it went right back to flipping back and forth between fix and single with it on single the majority of the time. This morning though I was getting the normal 36 satellites. My base station, also a Emlid Reach RS2 mounted on a roof, is working fine and has a fix. All corrections are coming through fine from my base station to the rover. I am using a Samsung Galaxy Tab A7 Lite which just did a software update this morning to T227USQS5CWD1. I use a Verizon Sim Card in the tablet to connect to the internet and then use hotspot to connect to the Rover.
Any thoughts? Could this be a global issue? OP what device are you using, is it also a Tab A7?