After the recent release I have seen a few instances of storage blocks not showing the correct items. I haven’t been able to tell but it appears to be when you move things around inside the smart stack and take things in and out. I have seen it with raw ore and raw coal in at least 3 of the spots.
Here are two screenshots. First is from outside the storage - notice top left. Second picture is inside that smart stack in the top left.
Yes open storage has this bug for a while now. Don’t know for how long exactly but i have been noticing it for about 3 months now. (Maybe 4 don’t precisely know but i started placing my open storage around that time).