I recently updated my phone to Android version 9 and OxygenOS version 9.0.11 on my ONEPLUS A5010 phone. Since this update, all of my other apps have worked fine (scrolling included), but in Blueline the practice mode has a stuttering quality -- once the auto-scrolling begins after the first few rows, it is no longer the smooth scrolling that it once was.
Unfortunately, I don't know enough about Android development to suggest a fix, but just thought I'd let you know. Thanks for all the work on Blueline -- I love and use this app all the time!