David,
I fear we're still "not talking the same language".
First, I would really like to know what's causing that. If it's a bug, it deserves to be fixed. So I still ask your help in my replicating the problem.
Second, this is not primarily for generating g-code "for only a part". It is to generate all of the g-code for an entire .cb file, and to separate it out into files by part.
Many folks have machines (and even I recently acquired one) that can manage g-code either in very small chunks, or for only one tool at a time (my big router doesn't allow tool-changes -- it's an 'extra-cost' option, costing over $2500USD just for the software changes!).
It was designed to address those sorts of problems.
(and yes, I'm going to re-do the control on that monster as soon as time permits!)
Lloyd