Sadly, missing assets are an ongoing issue. Some things will rez and some will not, even if you got them from the same grid. I had this issue the other day, trying to transfer a folder from my avatar on one grid to my grid. The workaround I found was for that avatar to put the items in a box and then teleport to my grid. I gave her rez rights so she could rez the box, and then I was able to take a copy of the contents, and then everything rezzed.
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