Hi Aaron,
2.5 Pro b4 seems to be creating HF mosaics with a fixed tile size of 512.
For example, I set up a 8x8 mosaic (16x16 DM) with tile size set to 128 and instead got a 2x2 mosaic of 512 size tiles.
An 8x8 mosaic (128x128 DM) with tile size set to 1024 will result in a 16x16 mosaic of 512 size tiles.
This only happens with the HF and not any of the other maps.