Upon doing the Jaheira's Curse quest we've done the following steps:
- Speak to Bernard - Speak to Corneil - Speak to Terrece - Go to Ployer's house
Upon entering Ployer's house nobody is there. We are playing a multiplayer game over Windows and OSX. We have even gone to our first autosave upon entering Athkatla from the starting area and retraced steps and still no Ployer.
Originally we went directly to the house upon getting the house did encounter Ployer with the mages but as we weren't ready for the fight we went to an earlier save and did the full quest.