When copying and pasting a set of blocks that includes a hanging lantern and the block it was hanging from, the chain that would normally symbolize a lantern that is hanging is not pasted with everything else. Probably the NBT data of the lantern is not being saved with the copy.

It's metadata? Does copy + paste work with other modded blocks?

Yeah, it's the only block added by this mod that has issues from what I've seen.

Where are you pasting the block? Are you trying to make a floating hanging lantern?

I am pasting the block attached to a fence-constructed lamp post. An example of what I'm copying and pasting is in the attached image.