The way the game handles saved arena tables seems to have changed.
I had to reload the arena tables in AvA as the one on the server seemed to have gotten corrupted, but when I went to look for the back up I had on my HDD, the game no longer recognized it.
They used to be stored in a subfolder with the terrain name in the ahiterr folder.
Any tables you have stored there will not be recognized by the game.
The new path seems to be a folder called "chconfig" which is loose in the aces high folder.
Once I moved my table files there, the game recognized it again.
Somehow it seemed to have been corrupted as well, but it got me closer than if I would have had to start all over.
Custom arena creators won't be uploading tables as a seperate process, but any you set up online will be listed as an "Arena Configuration File" when you begin creating your custom arena.
If I have something wrong here, I trust HTC will come along with the correct info.