My books app keeps on crashing

I’m a student and I downloaded a few textbooks on my iPad. Whenever I try to highlight or long press on a word, it get stuck there. I can’t extend the blue bar upto a sentence or access the options. Other apps work completely fine, I get go back to home, open control centre etc. but when I try to open then book after restarting the app, sometimes it doesn’t open and sometimes it just shows me the front page of the textbook, that’s it. It’s becoming hard for whenever I want to access by textbooks via my iPad. And yes, in removed and reinstalled the textbook but no difference. Help me find a solution for this. Thank you