Maybe this is a known issue, but I havent seen it exactly as I am about to describe it.
I was helping a friend with a build. She granted me permission to modify her objects. Two of the wall sections needed a bit of work, so I deleted the two panels that needed attention. I copied an existing wall to replace the two panels I deleted.
Once it was good to go, she could not link the build because the two copies I made of her wall belonged to me. So I went to sell her the originals. But, I could not change the permissions to allow her, the next owner, to modify or copy them. She was still able to buy them, but she could still not link those pieces because of the permissions snafu. I had to delete my copies and get her to make copies for it to work.
I sent a bug report, but too early for a reply. Just a heads up in case this problem with shared modify rights and broken permissions is not known to others planning similar work as I have described.