We first wait for the queue to assemble a party. It does find the team BUT mission doesn’t start and then the time resets.
After 15 minutes waiting I thought I could be doing something better, then I left the mercenary post.
Just encountered the same problem on the EU server. Tried both the mercenary post and the level 90 dungeon and had the same problem occur. Waits for about a minute, party then appears full and then the timer restarts and nothing happens.
What server were you playing on chpsoares?
Same issue on Orsha.
This is happening to me on Orsha right now as well. Guess I’ll go do something else…glad I didn’t use one of my exp tomes.
I’m playing on Orsha
This has been happened to me for a week, from 90 dungeon to mission. Getting tired with it when it took me the whole night to do 3 turns of dungeon OR 3 turns of mission. Ridiculous.
I am encountering the same issue here on Telsiai(SEA) server since yesterday 6am dungeon reset. The level 90 dungeon cant search for party and it takes forever.
What most players do, except some of them are dumber and wait in line for more than 30 minutes (me among them), crossing fingers. I took a break these days until next mainteinance to see if they fix it.
They did not fix it 19.04.2016 
This feeling sometimes arises that I’m on the CBT.