Notice the R in LIBERTY. It appears to have no center. I don't think this could be post mint because worn down metal would not fill the center like this. Is this a minting error or post-mint damage. Thanks
The middle circle of the "R" on the die broke - partially filling the die - producing a shallow strike with the circle filled.
I don't think it would be grease filled only - due to the fact the hole in the "R" is not visible and the "R" itself is significantly more than a ghostly type device on the coin.