Logos Mobil App shows blank page on download books working off-line

For a while now I have not been able to read any of my downloaded books while working off-line. when I open a book that has been downloaded while off line, I get a blank page. Or, if I do get a page with text, after turning a couple of pages, I get blank columns and eventually blank pages.

I am using an iPad Pro 10.5 with 256 Gigs of memory, IOS 10.3.3, and Logos mobil app 5.15.2 (5.15.2.0192)

I also had the same problem with my iPad Pro 9.7. 256 Gigs.

Any help will be appreciated.