Iron Citadel can't be completed (even with rares monsters + boss, all killed)

I would bet this doesn't complete due to the Count not technically being 'dead'. If they copied the code from the campaign, he technically doesn't die until Sin kills him, but he is on the ground panting in the map if you turn your sound up. Just a guess.

3 times now, i spend over 30mins to check all the corner

Same here

https://youtu.be/iRqXo0SvSd8

Same happened to me

This is still bugged. Killed the boss but had lightning chasing me until I had to just give up. Literally just ran circles for a good three minutes after killing the boss then died when trying to portal. I now have to find and citadel. Painful.

Have the same. I maked 3 iron citadel and only first is finished two next doesnt, and solution to fixup it?

Yeah, unfortunately it seems like it's still bugged. It happened to me twice right after the patch.