We recently discovered that Tridion Docs WebHelp output (Tri-pane DITA-OT plugin) is occasionally missing titles in the left TOC navigation pane. (Missing altogether in the file toc.html in the output bundle.)

I've tried to decipher the XSL in App\Utilities\DITA-OT\InfoShare\plugins\ishWebHelp\xsl\xslhtml\infoshare.dita2htm.toc.xsl but I confess that my XSL skills are lacking.

I have done quite a bit of digging in the XML source and can't find any patterns that might explain this. 

First I thought it might be outputclass attributes in map topicrefs. I don't think so now.

I wondered if we were building our maps or publications badly. But missing vs. not missing titles at the same level have the same hierarchy, i.e. chapter map, sub-map, topics. So I don't think so.

I wondered if we had a navtitle problem. It's true that we have a mix of topicref navtitle attributes in legacy data alongside the preferred topicref/topicmeta/navtitle element in newer maps. Again, I can't find a pattern in the XML that's different between missing vs. non missing titles in the output.

The basic question here, then, is, "Have any of you experienced users seen an issue like this before?"

[Tridion Docs 14 SP3]

Thanks for any feedback!

-Jay Baldwin