This is the conclusion of an article that talks about keeping various vitamins in balance.
As always, proper research should be done on amounts of any vitamin, what their cofactors are.
"Dietary deficiency of Iodine, Selenium and/or Molybdenum can lead to an
inability to activate dietary or supplemental vitamin B2. This in turn leads to
an inability to maintain the functional activity of vitamin B12. Prolonged lack
of active vitamin B2 eventually leads to an accumulation of inactive vitamin
B12 in serum, with a gradual increase in the absolute amount of serum B12.
Thus, elevated vitamin B12 is found in serum, yet the B12 is largely inactive,
leading to a condition of Paradoxical vitamin B12 deficiency."