'Show index tab for this language' does not appear to be working for me in DAB 3.0.1

Good morning, I’m trying to help build a project that has a Vernacular Language and 6 Analysis languages.
The team wants to have Tabs across the top for the Vernacular Language as well as 5 of the 6 Analysis languages. They were able to do this when the lexicon source was a lift file, but we’re trying to use an XHTML file as a source so that the abbreviations of the Analysis language will appear in the entry in DAB.

I’ve checked the box for the languages that says “Show Index Tab for this language”, but when I create the app, there are no tab’s and that box is unchecked in DAB. What am I doing wrong?
Thank you,