Which plugin version? Did you reload the Wiki after installing? That is required. Reload. Then dock.
Not sure I know what you mean "in the tab". Did you navigate to another html file?
The docking is the main reason I don't use tiddlyclip very often. I wish there was a way for a wiki to auto-dock itself.
There are other system-wide clipboard tools (like Ditto) that are sometimes easier to use, and don't require you to go back and forth with docking.