So I have experiencing this problem for weeks.
I filled up my retainer Bloesem with stuff to sell in her Bazaar and sent her off to the wards in Uldah.
When i tried to access her I get the message "You cannot summon that retainer right now". Apparantly she was also leasing a stand.
Also the client says she's in The Dunes.
So after making a GM call (which didn't help), I waited for weeks hoping that the leased stand would expire and she would return.

Now a couple of weeks later, I still got the same message as above, did another GM call with the same message from the GM's (Sorry we can't help you with this).

By coincidence I've found her! stuck on the other side of the Uldahn Mercantile House, and you guessed it... leasing a stand.... (see link for picture), which mind you isn't accesible because of an Invisible Barrier/Zone Line.
Picture link:So close... yet so far

Can anyone from Square-Enix please help me out with this

Thanks