As far as I'm concerned, it's not a bug since Finale based its calculations on parameters which are now different. Try re-entering the repeats after you have changed barline widths. Does that work?

Yes - I've tried the "wait till the end" idea as well. That's actually how I found the bug.  The gap appears in every scenerio I have tried - before/after, delete and re-enter, all for not...

If your statement "Finale based its calculation on parameters which are now different" were to be strictly enforced - nothing would update, including music spacing, much less ending enclosure line positioning. Also - if this were true, changing spacings for clef, key sig, time sig, triplet brackets, etc., or space between any editable item in the "Document Options" dialog box would not be recalculated/updated, nor would we need the "apply" button that becomes active in that window when a change is made.

I'm still convinced this is a bug...

Yeah, there are problems with repeat endings. There are worse than this, let me tell you.

But here's how to solve your particular problem. In Document Options>Repeats... click Repeat Endings (down at the bottom of the window.)

In the field "Inset for end of bracket" make it a tiny amount of a NEGATIVE amount, say, -.05 inches (or the equivalent in other measurement units). This will change the inset into an outset (is that a word?) that will make the first half it join the second half. However, this will also make the end of the hook of the second half move to the right by the same amount, which is probably NOT what you want.

What I do (regularly) is while in the score, select the handle at the end of the first half of the bracket, and nudge it right with the arrow a couple of clicks. This will transfer to all parts. If you only do this in the part, it will NOT transfer back to the score, nor to the other parts. You will have to do this every time you create a new ending. I agree that it is a bad design, and you should open a tech support ticket to complain about it, so that it gets moved up the "to do" list.

Thanks for the suggestions Christopher, I figured out the best workaround is simply manually dragging one of the enclosure lines to close the gap on each staff. Why MM tied both "Inset for end of bracket" adjustments together is unclear as I can't think of a single reason why they would need to be linked.

I could write a book on workarounds... since version 1.0, and I did start a support ticket on this issue...  often more weight is put on issues that get a good amount of chatter in any type of forum. That's why I posted it here - also - thanks again!!! Hopefully someone from MM will weigh in.

If I get any reply from MM, I will try and post it here.