I have a couple of Shadowlands legendary crafted items for different specs.
When I use the equipment manager to switch gear and specs it should also switch legendries (They are in different slots legs and cloak).
The gear no longer swaps as the in-game error message says that I can only equipment one legendary at a time.
I am not equipping two just swapping one for another.
If I remove the legendries out of equipment manager setup then gear/spec swaps okay.