Yeah... this is a bug in the Blizzard world frame that affects all addons that create a viewport. It's because of how and where some of the textures are anchored... some of them ignore the viewport, others do not.
I'm going to put out another update with an option to turn the viewport on and off so you an use the viewport when you are elsewhere in the world and turn the viewport off when you're in parts of the world that are broken.
It should be out later tonight or tomorrow morning.
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