[AccessD] database prevented from being opened or locked

I would like to drag and drop objects from one opened Access database to another. Visually this looks like it ought to be possible, however in practice it never seems to work. No matter whether I open the target database in the Access Open dialog either with
	Open
	Open Exclusive
	Open in Microsoft Access

I always get the message about the database has been placed in a state which prevents it from being opened or locked.

I also have tried it all 3 ways with or without Shift held, and that makes no difference to this attempted (and failed) operation.

I am the only user of the database:  is there a way to be able to perform these kind of steps without using VBA or Export/Import using an unopened database?