Is it possible for items in workshops to be shared in other workshops? My items have all dissapeared, and yes I have supply lines... They are still in sanctuary, but not showing up in Covenant... PLUS All the wooden floors etc I put away don't transfer over!?
You seem to have two issues.
Items that go into workshops are not available at other settlements except for crafting. You can't just pull them out, but you can use them. For example, you can put duct tape into Sanctuary, and you can use it to make mods in Red Rocket, but you can't pull Duct Tape out of Red Rocket's workshops.
You CAN NOT transfer entities between settlements. If you store a generator in Sanctuary, you can only pull it out at Sanctuary. At Red Rocket, you need to build a new one.