Once you select one of the Horde exploration guides it throws an error and then refuses to open the guide selection window again.
Here's a quick fix you can perform until we can get it fixed in an update:
1. Navigate to WoW/Interface/AddOns/ZygorGuidesViewer/Guides and open the ZygorIncludesHorde.lua file with your favorite text editor
2. Search for: label "+zul1"
3. Replace with: label "zul1"
4. Save the file
Here's a quick fix you can perform until we can get it fixed in an update:
1. Navigate to WoW/Interface/AddOns/ZygorGuidesViewer/Guides and open the ZygorIncludesHorde.lua file with your favorite text editor
2. Search for: label "+zul1"
3. Replace with: label "zul1"
4. Save the file