This seems to be quite a moving target. Based on past solutions, I was able to dig in figure out why this was broken (again).
In `Objective-C.tmbundle/Support/lib/docset_query.rb`, I had to change line 10 from
DOCSETS = Dir.glob("/Developer/Documentation/DocSets/*.docset”)
to
DOCSETS = Dir.glob("/Library/Developer/Shared/Documentation/DocSets/*.docset”)
Anyone else run into this?