Can you read offline with Borrowbox (android app for audiobooks and ebooks with local library)?

I know it's possible but I've never managed to get it to work.

I've chosen a book and it downloads on WiFi and then I read a few pages. I shut WiFi off which causes the next pages to become blank and scrolling to find all pages are blank.

If WiFi is turned off and I open Borrowbox and then the (already downloaded) book it just endlessly loads on front page.

So I need a connection to open or read a book. I've tried uninstalling and reinstalling, giving access to storage and no restrictions on battery.

I've already asked on here before a while back but does anyone have Borrowbox and can read books offline?

I've contacted Bolinda again as the previous time I gave photos, detailed explanation and log report but they never got back to me after the log report.

TIA.