Been tearing my hair out with this one and I've run out of things to try. I'm hoping it's just a silly bug, but it may be some feature of the hardware I don't understand?!?
I have a sprite that is scaled to 50% H&V (SCB2=0x077f). That bit works fine. The Y location is 0x1F0 (top of visible area) and size (sprite window size) is set to 14 in SCB3. That equates to 14*16=224 pixels.
However, the sprite doesn't look like it should; the latter half (approximately) is a repeat of the bottom line of tile index #15 as per the wiki docs (and on this matter I don't understand as there are 32 tiles in a sprite).
This isn't supposed to happen unless the shrunken size is smaller than the sprite window. In my case, shrunken size (50% of 512) is 256, whereas the window is 224 pixels. I should see 28 of my tiles.
If I try shrinking the window to 8, it works fine; the sprite is 8*16=128 pixels high and the tiles look good. Of course that equates to 16 tiles visible in the sprite. Setting size to 9 or higher gives the right window height, but nothing past the 16th tile...
I should add, if I set my height to 33 instead if 14, I can see 28 tiles properly, but that's not how I need it to work. It's like the latter 16 tiles can only be used if height == 33???
Can anyone shed any light on this please?