ISP:
Bell Aliant

Type of Internet Connection:
Fiber

Internet Connection Speed:
Unknown

Date & Time:
September 7, 2016. Around 12:00pm AST

Frequency:
Once (Did not reproduce)

World:
Behemoth

Character Name:
Leliana Eorl

Retainer Name:
None

NPC Name:
None

Monster Name:
None

Class/Level:
Paladin / 54

Party or Solo:
Party / 4

Race:
Lalafel F

In-Game Time:
Unknown (I can't remember)

Area and Coordinates:
Palace of the Dead

Housing:
None

Steps:

1. I had queued for Palace of the Dead, Floor 41, on my 54 Paladin. When the queue popped, I accepted. It was for an in-progress Floor 44 with 15 minutes of time used. When I loaded, it was into a room with no doors, and no cairn.

2. The others proceeded to finish the floor, but we found that they could not go to the next floor as I was not physically at the Cairn of Passage.

3. They proceeded to kill more monsters and attempted to use the Cairn of Return, hoping it would bring me there. It did not.

In order to continue, they had to kick me from the group or else lose all their progress as well. I used no macro. And there was no error message.

The only thing we could think was that I possibly loaded in during a floor change, which through me into a non-existent room but put them in the proper room. None of my friends have heard of this happening before, and my party members were just as confused as I was. I could still see the map, and where they were on the map. So I was on the floor, but in an unconnected room. I could see the item list, and they were lit up so I could use them. I did not attempt though.
And in all honesty, while it looked just like it was supposed to, the emptiness and lack of doors really made it feel like a jail cell.

Hopefully you can find out what caused this and fix it.

Further joining of in-progress floors did not repeat the incident.