Out of curiosity has anyone tried clearing the region's cache? Assets basically flow like this: Robust -> Sim (cached) -> Viewer (cached). If there's a network hiccup between the sim and robust during the initial fetch, then what's in the sim and viewer cache will be broken. If there's a hiccup on the disk the sim is caching to, then what's in the sim and viewer will be broken.
In the case of an HG transfer, I believe the assets going to the foreign grid are going through the region's cache so... Those could likely be affected to.
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