Use RANK() instead of INDEX(). The latter is really not meant for sorting.
RANK( SUM([Number of Records]) )
Then replace [index] with [Rank] on your Rows shelf and configure the table calc the same way that [index] was configured.
This gives me the output I need. Forgot about rank! Great solution!
Still interesting to see why the sort box isn't giving me desired output- with or without INDEX().
Also kind of confusing to see that the KB article isn't using rank as well.
That KB article is very old and has a disclaimer at the top that it's no longer actively maintained. It may even predate the introduction of the RANK() functions. (The screenshot shows a very old version of the calculation editor.)
When you do a simple sort on [Type of Guy], the reason you get odd results is that Tableau is sorting [Type of Guy] the same way for all [Business] segments. (Presumably it's basing the sort off the TOTAL across all [Business] segments, at that point.) There are advantages to this behavior in some cases, but it's not always what you want. That's where RANK() becomes useful; it allows you to sort [Type of Guy] differently within each [Business] segment.
Everything you said is true! Still a bummer it wasn't "updated" yet.
I'm also a dummy and forgot about this video: Fixing "Incorrect" Sorts with INDEX()
It also solved my issue, but RANK still takes the cake here.
I should've searched a few minutes longer.
Thanks for your help and your activity on the forums!