Despite thinking I was done with this style, I found another issue with the in-line citations where I am trying to disambiguate multiple citations by the same author in both the same and different years.

What I want is:

(Khan et al. 1980; Lance et al. 1985; Thorbjarnarson 1993a,b, 1996; Hekkala et al. 2011; Shirley 2014)

What I get is:

(Khan et al. 1980; Lance et al. 1985; Thorbjarnarson 1993a; b, 1996; Hekkala et al. 2011; Shirley 2014)

Interesting enough, adding the citation in a different year by the same author seems to overcome the previously discovered bug, see:

https://forums.zotero.org/discussion/57178/citeprocbug-format-error-with-disambiguated-inline-cites/#Item_13

Or is this possibly the same bug?

Here is the relevant CSL code:

<citation et-al-min="3" et-al-use-first="1" disambiguate-add-year-suffix="true" collapse="year-suffix" year-suffix-delimiter="," after-collapse-delimiter="; " disambiguate-add-givenname="true" givenname-disambiguation-rule="by-cite">
<sort>
<key macro="year-date"/>
<key macro="author-short"/>
</sort>
<layout delimiter="; " prefix="(" suffix=")">
<group delimiter=" ">
<text macro="author-short"/>
<text macro="year-date"/>
</group>
</layout>
</citation>

This style has been validated and tested.

Thanks!

Matt