I've run into an issue with InD 16.0 (2021). A recent epub has exported with both English:US and Arabic in the OPF causing display and backward flow issues on Net Galley. (It displays fine on iBooks and the Kindle Previewer.) I get no validation issues. It was brought to our attention by Net Galley:
We received an email today from a NetGalley member using the NetGalley Shelf app and she reported:
The formatting of the book is very odd because the punctuation does not appear as it should; the punctuation appears at the beginning of the line. It has made it difficult to read. It also turns pages the wrong way, but that issue is not as bothersome as the punctuation. I was wondering if you would be able to send me another digital copy so I might be able to review the book.
Here is a screen shot of the line in the OPF:
I have since removed the line for Arabic (ar-SA) and rezipped the epub. It tests and displays fine/valid. It'll be resubmitted to Net Galley and I hope to hear back.
Note: I did check the InDesign file for language in the file prefs and all the style sheets and English:US is selected everywhere. It's using Berkeley Oldstyle OTF, a font I used on a previous ebook just a week or two before, with the SAME stylesheets, and it doesn't have the Arabic language line in the OPF. I believe it was from the same version of InDesign, but could possibly have been one update back?
Really unsure why it would have done this. One more thing we have to check everytime we export, or is this a new bug?