With iOS 13 due out in a couple weeks, I started testing compatibility with Walkout Songs. The tests did not go well so far with the most glaring issues being a black screen when trying to chose songs from the iTunes library and an app hang when the app is closed and reopened after playing a song.
Some of the issues go away when tested against iOS 13.1 which is due for release 11 days after 13 so I'm pretty sure Apple knows there were some glaring issues with 13 and I would suggest waiting for 13.1 and a new update from me to clean up the compatibility problems I can fix.