Using LT 2015 with 10.10.2 (actually 10.10.3 Beta, but this has been happening since long before this beta)

Outside of the block editor, if I create a box and then duplicate that box (Apple+C , Apple+V) and select a grip on one of the boxes, I can drag it and connect it to an end point on the original box and it lines up perfectly.  I verified this by zooming in some insane amount (I can't never actually tell what the current zoom level is.  Is there a thing for that?):

I have a block.  Within that block there is another block of a box.  If I do the same thing, duplicate the block of a box inside the other block (this is starting to sound like a Dr. Seuss poem!) using copy/paste and try to line them up, they just won't do it:

I've even gone ahead to make sure that the the top-left side of the box block is 0,0,0:

I just don't get what I'm doing wrong here.  It's wreaking havoc on my drawing because I expect the copy/paste/move grip to connect to an endpoint and align itself perfectly no matter if I'm drawing a box or using a block.

Thanks in advance!