Just went searching for a fix to a problem I had... wanted to throw my .02$ in.
I mostly work in Inventor, and have for a while now. Sometimes, we have an old AutoCAD dwg to edit, which doesn't make sense to completely redraw. We have a situation where we need to get a newly crafted Inventor title block (or sketch symbol) inserted into an old AutoCAD dwg. So, in the past, I'd save the Inventor .idw to a .dwg, the title block (or sketch symbol) would be converted to a block, which I could copy-paste into the old AutoCAD dwg, and it would look fine, and work fine. Just tried it for the first time in 2013, on Windows 7, and the block in the converted .dwg basically wouldn't copy at all. It would seem to be working... could see the block, select the block, initiate the command, specify an insertion point... nothing would be created. Not across dwgs, not even within the same file. Also, typically the "prompted entry" fields would be converted to "block attributes" (...or whatever they might call them now, lol)... not the case now. I checked the layer situation... all seemed good. No idea. Solution was to explode the block, and copy-paste that, which did work... though obviously not an elegant or fully functional solution. Don't know... weird... something seems borked w/ AutoCAD 2013s handling of blocks.
If you have another suggestion that is more elegant, I'm all ears.