epub not showing all pages or content in Books

I have an epub file that worked fine in Books until this week. The file was exported from InDesign in epub version 2 reflowable file format. It only contains text, no images or interactive content.

Now it is missing most of the pages and content (seems to grab a random section part way through each chapter and has gone from 300+ pages to less than 50).

I am able to open the same file on the desktop version of Books, as well as other epub readers without any issues. Other people with iPhones are also unable to open this same file (different iPhone versions).

I have followed the steps recommended here with no success: Ibook not showing all pages on iphone - Apple Community

Are there any other steps to take, or known issues with ePubs currently?