Here are the most common problem, which can all be solved easily.
Smart tunes don't play
Make sure you use Google Chrome as your browser. Safari can cause this issue. Some other browsers may cause issues as well.
Smart tunes have no sound on iPad/iPhone
Solution on the soundslice website here: Troubleshooting no sound on IOS
Transpose is doing weird stuff
Open settings on a smart tune/practice track and UNCHECK "Transpose audio playback".