Listening instrumental music and reading should use different parts of the brain, is it should be compatible.
However, what will occur memory wise, is that that music will be associated with what you're reading. So you will remember that music when you'll remember or read that text again, and you'll remember that text when you'll listen to that music again.
This only works very well with novels. When i was younger, i made a quite terrible habit out of this. I read the entire Wheel of Times Series with "He lives in you(Diana Ross version). It got so bad, i couldn't read any Wheel of Time book without playing that. I read the initial Mistborn set with Viva Forever etc etc. I put a stop to it a few years ago.
What you have to realize is that, this works with only soft reading when you don't really need much "brain power" to process what you're reading. Playing epic music while reading Epic fantasy helps with the visualization process and scene buildup.
I don't see how anyone is going to retain long term memory playing Viva Forever while reading Donald Knuth's TAOCP but it's just MO. If you want a more indepth look at the topic, you should try out Barbara Oakley's "A mind for numbers". Touches briefly on these kinds of background distraction while reading/learning.
If I’m in a coffeeshop and there’s a hum of noise I want to drown I’ll listen to some music. AFAIK I have no problems focusing or collating the text while doing this.
But if I’m at home, where there’s no noise other than occasional traffic, and try to listen to music, I tend to lose focus and seek to multitask with something else. ¯\_(ツ)_/¯
I’m thinking it’s because my mind is looking for a mellow state to get into while reading a book. The music in the coffeeshop example ends up just being whitenoise but becomes more of a conscious burden when I’m already in a quiet environment. This behaviour is also very different if I program, where listenin to music always seems to put me in a the right state.