It seems to be a bug that happens on my phone only because it works on my wife's phone. I have the latest version on my phone and on the computer.
See attached movie to see what happens.
It starts playing a song and at 3 seconds when I try to switch to a local file (clicking on the computer) it stops the music and quickly flashes a message where the current song name usually appears. I try to click more times and it flashes again. Then I switch back to the Spotify song and it starts paying and I switch to the screen that shows the album picture and when I try to switch to the local file it closes this screen and goes back to the previous one.
If at least it was crashing I could send a crash report.