Yeah thats exactly it. It's overlapping very slightly with the block on the right which is an indestructible block. So I'm just updating that code to ignore overlaps with indestructible blocks.
I'll try push an update later today with this fix as well as a couple of other ones.
Unfortunately web builds come with a bunch of annoying problems and because so many people are playing im a bit nervous about pushing a big update and accidentally causing other (potentially worse) issues.