When creating my model (the exact tree sprite that comes with the demo), I notice that zscale is affecting the position of the object by making the base z position appear higher than its actual z position (double checked using debug messages upon creation). That is to say, if an object's z value is 64, and zscale is 1, the object will appear on the z-axis correctly, at 64. But if the object's z value is 64 and zscale is 2, the object will appear on the z-axis somewhere closer to 96 or so. I also notice that this gap is larger when the z value is larger, but only if zscale is above 1.

(edit: tested with zscale values below 1, and I can confirm that the objects' z positions appear lower than they're intended to.)

Create event: 

//var scl = (random number between 1 and 2)

//var z = (dependent on position, but often between 0 and 128)

// Create model

var model = fauxton_model_create(sprite_index, x, y, z, 0, 0, image_angle, scl, scl, scl);

fauxton_model_add_static(model, "PropBuffer");

// Cleanup

fauxton_model_destroy(model);

instance_destroy();

Any help is appreciated!

Doing a bit of a deeper dive, it seems like it only happens with the static buffer models, and not the original models. Going to check out some of those functions, and if I can't find a fix I'll see if my game can handle leaving the models in without creating static buffers (although I'd imagine this would cause a bit of a performance hitch down the line with large rooms)