The buttons on ground act like a permanent pressure plate when an arrow entity is on them. Any buttons near the button with arrow behave the same.
How to recreate the bug:

Make a patch of buttons on the ground, I made it 6X6.
Stand in the middle of the patch, on a button and /summon Arrow.
Now walk on any button, they will act like pressure plates and will emit redstone signal.

If you remove the arrow, all the buttons will update. See the pictures for a better understanding.