Android 5.7.x. wakes up in different mode,error/failure

I start Android app 5.7.x.
I select an album to listen music.
I put aside the Android…
Meanwhile the Android goes to sleep/standby.
When Android wakes up (to choose another album/music) the last screen of Rose Connect is lost, the connection to the RS520 as well and a new screen appears like this…

It forces me to select a device