All the chests in a chunk in my world were deleted, leaving behind a ghost block that cannot be interacted with.
Inspecting the world with MCCToolchest, I found that all tile entites in that chunk were deleted - so even though the hoppers and pistons still appeared to be there, the tile entity information for them was not.

World files below. Affected chunk is 4,0. Chests are at 70, 57, 13

Before issue: https://drive.google.com/file/d/1Lisqr5KgjjwudXN6fldxecG7UuKhTYo9/view?usp=sharing
After issue:https://drive.google.com/file/d/1y92PyRFnCXh1m-lWSL_g1DKHaNmNalVB/view?usp=sharing