This has happened twice now. Once, I thought was just a wierd fluke. The second time, I lost my dungeon queue.
First time, I was porting to Vivec City from Cyrodiil from the Southern High Rock Wayshrine (PC/NA, Grayhost, DC).
The second time (the next day), I was porting from a Craglorn wayshrine to a Deshaan wayshrine. Different account (PC/NA).
Each time it was a seamless transition as if I had simply deliberately logged out to Character Select.
There was no noticable lag or ping issues at either time. Both times I could log back into the impacted character immediately.