Vendor Problems

I am having a problem with accessing NPC vendors. When I click on a vendor my inventory opens, but the NPC vendor inventory does not, and I am unable to buy or sell any items. Is this a bug, or is it a problem with my settings? The issue started with the game update yesterday (Update 7.5), when I initiated the new content and started the Basillisk Venture quests. Any assistance would be greatly appreciated. Thanks.

This occurs when I am logging in through the PC platform, AND through the Steam platform. And is occurring with all my characters. Thanks.