It might be your cfg files.
C:\Hitech Creations\Aces High Editors\settings\ahobj.cfg
C:\Hitech Creations\Aces High Editors\settings\ahobepos.cfg
Rename them and let the Object Editor recreate them.
The offending tile might be missing or include custom shapes you no longer have on your HD in the userlib folder, or even older default shape that have been removed (rare) from the available shapes.