you can't join if you're in the middle of a run already.
if you're at the portal before you "ping" for astaroth dungeon you can, otherwise you're locked in there solo buddy
yes, exactly.
I was before initiating encounter / entering portal.
Anyway we faced other issue with teaming up (code xxxxx blabla). Seems not on my end as I was able to party up with my wife's char.
I gave up and gone bed.