Yes I get the same issue when running DX11. DX9 works fine but for some reason DX11 will freeze like you mention after one of the earlier patches of Heavensward. If I have kept my computer up running and log into the game and if I have loaded those areas previously it seems to work, however, if I shut my computer down and then go back in fresh, more than likely it will freeze. Although Alt-tabbing out will also freeze the game in DX11 for me. Again this started happening like after patch 3.1 or so. Initial Heavensward release worked fine.