For example: here we can see this rendered LaTeX formula but in the PDF version it uses both columns, so we cannot read it correctly.
BookManager is not used on Wikimedia sites so this is probably about OCG-PDFRenderer
Oh, thank you! I'm newbie here
As already announced in Tech News, OfflineContentGenerator (OCG) will not be used anymore after October 1st, 2017 on Wikimedia sites. OCG will be replaced by Electron. You can read more on mediawiki.org.
No longer an issue with the new Proton PDF rendering