Okay, this is my latest record, I need a break :D Man, you should never build towers out of pebbles. It's too easy to lose while the tower becomes taller.
And yeah, it was fixed once the pebble became unbound again. So I think it happens when the switcher is activated but then pebble is modified (grows or shrinks) while still being bound.
Might've encountered a small bug on the Spooky mode in v1.2.4: when the switcher is activated (pebble becomes "bound") it may behave abnormally, like not pushing the other pebbles enough (overlaying them). See the screenshot below, on the bottom right.
