Just had a look at the style's source (title-short macro specifically).
It will print the short title for "bill book graphic legal_case legislation motion_picture report song" (that's the CSL item types; names vary in Zotero).

What item type do you not get the short title? What do the guidelines say about it?

Thanks for the replies. I've noticed that the short titles appear for subsequent citations of books, but not for journal articles and theses. However, short titles ought to be used for citations of all sources according to SBL requirements.

This seems to be a recent problem: when I checked older documents that I worked on earlier this week, the citations for articles and theses reflect the abbreviated titles. However, once I click "refresh", these citations get updated with the longer titles, and my word count jumps by a few 100 words...

I just pushed out a fix for this, should automatically update for you shortly. Sorry for the trouble.

I'm having the same issue, JFJW. Today my Zotero automatically refreshed my document and turned the "Short Title" for journals and theses back into the "[Long] Title". I have had no luck on a fix for the problem - glad to know that I'm not the only one, though.

@adamsmith, sorry I was out of the office and am just now seeing this. But yes, SBL style does want short titles for everything (though there might be an odd exception I'm not thinking of at the moment). And thanks for remedying the error.

@JFJW, @nsheley, and @TylerHallstrom, my apologies for contributing to the momentary elongation of your titles. I must have missed that error in some of the recent editing for the style. But it should now also have improved support for citations of (1) lexicons; (2) dictionaries; (3) conference papers, and (4) DOIs, URLs, both, or neither for various source types.