Yes, it is possible to fix.
Use an older TileData.mul for Sphere to load or edit your current one properly.
If you do not know how to edit the TileData.mul, I suggest using an older one.
You can get an older one that works by installing an old version of Ultima Online such as Renaissance or The Second Age and copy over TileData.mul before running UOPatch.exe.
Sphere 51a is old, and as such it should be running on older files and you are running it on newer ones and that is why you are having such problems.