[SOLVED] Weird positioning of tiles in tile pallette

Not really sure how to explain this one without using images. Basically, I'm taking a 512*512 image, splitting it into 256 tiles of size 32 and putting it into a tile palette. I expect to get a 16*16 setup in the palette, but instead I get a 17*16 tile setup in the palette, where line n has an offset of n tiles from the setup I want. Surely there is no logical reason for it to pick 17*16 instead of 16*16?

See picture 1 for original tileset and picture 2 for result in tile palette. In this...

[SOLVED] Weird positioning of tiles in tile pallette