I used Muscle Through on Tvericus, who is 2x2. When it came to the "Slide 1" part, the possible destinations/arrows were centered on his model like usual . . . but since he's 2x2, his center was halfway off the grid. The result was a misaligned image. See here: I thought this had already been reported, but I can't find it, so here you go. (And I'd rather not host a million images that will go obsolete, so I'll delete this once we're done with relevant bug smashing.)
It's actually properly aligned - that shows where the centre of the figure will be if you move it. I admit it doesn't look very good though and we need to do a bit of work to make it clearer.
Huh, yes, that would be logical. However, while mousing over the spaces, I still get four squares to light up under the mouse: it doesn't, say, light up centerpoints. Thus, this aligned/misaligned grid is the only one that uses such a principle, and kinda looks funky.