While creating an Ingot (Greensteel) the DC for creation began alternating between 16, the actual DC, and 36.
I had 131 coal and 11 arjale in the anvil for the first ingot creation.
I had 129 coal, 9 arjale, and 1 ingot (greensteel) in the anvil for the second ingot creation.
For these first two attempts I had 22 smithing.
I then increased my smithing to 24, had only 2 arjale and 2 coal in the anvil, and still faced the alternating DC's.
Steps to reproduce the Bug:
Attempt to make a ingot (greensteel) per usual.
Expected Result:
Simply produce the ingot (greensteel) on the 16 DC by itself.
Actual Result:
DC to create alternates between 16 and 36. DC is truly 36, because I failed it multiple times.
Screenshot(s)

Additional Information/Notes
Used a player-created anvil.