Hi. New user here (impressed so far!). I imported my local server, and most of it works fine. I’ve got my characters, macros, and such. However, in Foundry itself, character portraits and other assets aren’t working. They do appear to have imported as they are showing in the asset manager.
Looking at the console while in a game, I see things like this (I expect this was the path it was using with self-hosting):
Cannot GET /CotCT/PCs/Yulia.png
Looking in the asset manager, I see very different URLs for the character portrait that is trying to load:
https://assets.forge-vtt.com/serverId/foundrydata/CotCT/PCs/Yulia.png?optimizer=disabled
Did I do something wrong in uploading it? I picked the foundry data folder. Or do I just have to manually relink these to the new assets?
Thanks. 
I was able to solve it. Everything ended up insdie a /foundrydata folder inside the asset manager. I moved everything in that up one level to root, and now the character tokens and such are all loading.
Not sure how I managed to get it into that state in the first place, but it’s good now.
Glad you got it fixed!
You might want to export your world and re-import it so it would change the links in the world to use the assets library. Right now, since when the world was imported, the assets weren’t in your assets library (under the right path), the world was pointing to files that didn’t exist. When you fixed it, it will still point to the files in the server, which don’t exist, and the Forge will catch those errors and proxy to the assets library, which means that it works, but it won’t be optimized as it wouldn’t actually be using the 54 geo distributed assets library servers.