I always come back to this one
In 50 years of playing music, I never learned how to read music until I learned to play drums about 10 years ago. Then I gave violin a try, but even though I grew to hate that miserable little instrument, I did eventually learn to automatically place my fingers based on what I was seeing on the sheet music. Bass has always been my primary instrument but I learned by ear or tabs. But tabs are worthless if you’ve never heard the song before. This is the one and only app I use now to learn and improve my bass clef reading and playing. It’s direct and not filled up with a bunch of superfluous crap on the interface. Basically, it just works and works well. Get it and put the time in and you won’t regret it.