Black Lion Trading will not work Mac
You can try clearing the GW2 cache. (Instructions [for Windows] found in the Knowledge Base accessed via the ‘Support’ link above/below.)
Good luck.
Black Lion Trading will not work Mac
in Account & Technical Support
Posted by: penelopehannibal.8947
To clear the cache for Mac, go to your desktop, making sure it’s got ‘Finder’ next to the apple symbol.
Hold [Alt] and select ‘Go’ dropdown menu. When you hold [Alt] whilst doing this, a ‘hidden’ menu should appear called Library. Click that, then find the folder ‘Caches’.
In that folder should be another folder called com.transgaming.guildwars2. If you drag that folder to the trash can, it should fix the TP problem. 
Blood & Merlot [Wine]
They should add that to the Knowledge Base. Thanks, penelopehannibal!