This is an issue from poe.ninja side. The data that we extract from their API is giving the wrong information.
I've updated my fork with a min-max price range for unique with multiple variant. It's not that useful but better than nothing.
Most thing that show as 0c are either not handled by the API or pretty much just worthless.
Also, Ancient Orb was giving the wrong info for multiple weeks now, I've put a temporary fix today but it just got fixed from their API apparently. What a strange coincidence.
Make sure to reload the API data at least once per day, this might be why it show the wrong data.
But for your question, check what happened to Orb of Unmaking there:
poe.ninja
According to the chart, the price of Orb of Unmaking dropped to 0.07c for buyout.