I saw this phenomenon happen to my Co-flyer last week on his Ipad though no app switching was invoved. I, however, acheived flawless connection on my Android for both legs.
On the outbound, he lost SD connection to the Rosetta for about 15 minutes, he was concentrating on flying and it finally regained connection by itself to be stable for the rest of the flight.
On the return leg, try as he might, he couldn't get his iPad to connect on 'Pilotaware' mode. Rebooted it twice, restarted WiFi etc. He finally acheived a stable connection after I suggested he switched to 'Flarm' connection mode, after which it was faultless.
His Device:
Ipad Mini 2 32GB, IOS 12.3.1
this isnt the originally reported issue - sounds like you just lost the wifi connection entirely?
definitive response given on the SD support forum about switching ios apps to background Summary: it will not support a continued gps feed VIA WIFI if the app is put in background mode. Tim Dawson states this a limitation of IOS so not an issue SD can do anything about.