I have dealt with Korlasz in the beginning of the Siege of dragonspear. Then I stuck, so I have searched the internet and I have found, that I can exit the tomb talking to Imoen. But I cannot find her (she disappeared along with the Flaming fist buddies) in the tomb anymore. Actually, last time I saw them was when I handled them Porios right behind his door. Does anyone have similar problem in the game? Is there a solution? Thank for replies.

its not a bug but a story plot point i.e, Imoen does not come with you in dragonspear because she has to stay and work on her magic training... Korlasz is taken to the cells [assuming you did not kill her] and can be seen again or just skipped

Imoen can make a few camios during dragonspear and may even rejoin you at the end before heading onto Bg2

Thank you for the reply. How can I exit the tomb after killing (she was not willing to surrender) Korlasz then?

go back upstairs to the first room you started the tomb in [after you grab all the loot]

Imoen and any fists that are still alive should be in that room waiting to leave... be sure to finish up any quest points before you go because this area is locked after you exit

But as I wrote in the first post: Imoen and Flaming fist mercenaries disappeared; I can't find them anywhere.

yes but you didn't say why
1 if Imoen takes damage she will teleport out
2 if you move between area loads she appears in the new area

in any event the room you started in is the way out and there is a rope hanging down from the roof you can click on

Using the rope only says that it is the only way out and nothing more happens. Imoen is nowhere to be seen.
I think I just try to start over as it is just a mere beginning of the game.
Thank you for the insights.

Edit: I gave it one last try and I found her! She was hiding behind a wall near the spot where I saw Porios for the first time. Her Flaming fist buddies age gone though. Anyway, Is there something like a console command, for example, hinting where an NPC could be?

I know you found her and that this is a very old thread but I wanted to post here for others as well: I had the same issue. Imoen disappeared. I had to search the dungeon for her. Eventually I found her near the stairs back out of the catacombs. Clear a glitch because she says her and the flaming fist are going to take the rope just south of them to head back to the entrance.