Problem:
Some users of the Guild Wars 2 client for Mac OS might have experienced the in-app trading-post not working.This seems to be caused by remaining wine/etc. processes that are launched by the Windows Emulation-Layers that come with the Mac Client. It seems like not all processes are killed/updated when you stop and relaunch the game. A more detailed explanation can be found on the official boards here:
https://forum-en.guildwars2.com/forum/support/bugs/Mac-Beta-Trading-Post-Issues/first#post3156901
Solution:
Exit GW2, then check the process viewer for the following running processes and kill them:– wineserver
– CVMCompiler
– cookied
– (two instances of) Guild Wars 2
Not neccessarily all of them might be running. In my case, only cookied seemed to have been "left over".