If I recall correctly, because I'm sure I did it, we used to be able to move assets between clients. This was useful for say, a firewall we owned, but a client was leasing.
Now, in both our instance and the demo, the only options under the dots are edit, copy and archive?
So, if I'm right, tis a bug. If not, then it's going to be a feature request 🙂
Edit: It's under bulk actions, even if you need to move a single item. Select the check box and then go to bulk actions, Transfer to client. Locking this, but leaving in case someone searches for the answer…