The last few versions have failed to load custom assets and the hall of mirrors in the skybox is indicative of a leak. I've considered the possibility it might be my computer being screwy but I load other maps before and after Rio, which have custom assets, and work fine. Eons ago when I mapped I had the issue of assuming a map packed correctly when in reality it had not and was still pulling custom assets from the directories on my computer. Prior to loading it for a final test before an upload I rename my custom directories so it has to pull any assets from what you pack in the map assuring it is packed correctly. Still that wouldn't explain the hall of mirrors in your skybox, that's always been a leak when I've seen it in my maps.
You clearly are a skilled mapper and I hadn't commented before because I thought it was a one off error but it's happened in several versions now and I wanted to say something before "the big one". Maybe get someone else to load it up to be sure?
