EPUB not searchable

[NIRC]

EPUB books in fixed layout that are generated from an InDesign “book” containing multiple files are not searchable with iPad’s iBook reader, though other readers have no problem with the search function. I assume this is a bug

[Eugene Tyson · Accepted solution]

Works on others but not with Apple?
Seems like an Apple bug to me. 

https://discussions.apple.com/thread/8556519