"Below the ground" npcs are imho those, that the game still has to load models and/or textures for. If they do not appear within few seconds, there might be corrupted resources of that npcs in resource databases. Repair/Compact game files might help (option in game launcher).
i also did the quest today (23 may) and he was there (no problems for me)...
but you wrote your post on 10th of may, the same date of update 3.3.4 (it may have caused some bug there)...
Hmmm... that thing with the NPC below the ground is nothing new (happens everywhere since I can remember) - but normally they show up after a few seconds when you come near them (it happens only if there's a lag with creating the playfield for you).
your computer may be slow or not loading things fast enough:
- do you have stuff in your computer background tasks?
- are you using internet connection for other things with the game at the same time?
- have you got drivers updated for the graphics card (usually the game detects if your drivers are not updated)?
- do you have firewall/antivirus protection (configurations)?
- wait a few more seconds to see if he shows up (loading)
- repair your data in the launcher (takes some time for it)
- try do decrease graphic quality to minimum of minimums
- stop the maximum of task applications running in the background
- update drivers if necessary (for graphics card at least)
- go to www.speedtest.net/ and test your internet speed to check the lag (pings)
- check your firewall and antivirus configurations
- in worse case scenario just format your hard drive and reinstall windows + drivers + game + windows updates and try the game
just found out from a player in game that a GM told him its an issue common to new installation or recent game installations (last time i've install this game was last year, maybe that's why i don't have problems)..
so, newcomer's may be the only ones having this issue, correct me if necessary...