Except bumping with “still bugged” - I just want, also add bit more details to the problem(s) description here.
For the very starters, it is pretty easy to find reports (which are atleast 2.5 years old) regarding the another bug with Chess event, by googling “wow karazhan game in session debuff”.
Definitely worth of mentioning - situation with that bug also didn’t changed for years, you still are forced to talk with “Echo of Medivh” before leaving the Chess room because of " Game In Session" buff. Which does not disappears from your char automatically (after event is winned or lost, immediately or by a few time passed) as it MUST.
Dear blizzard devs - do you really considering that as “normal, working as intended”? Let’s hope, you do not…