Green Cobalt(II) hydroxide in D2O

I reacted Potassium metal with Deuterium oxide in order to yield a basic solution of Potassium deuteroxide. I then added Cobalt(II) chloride to precipitate Cobalt(II) deuteroxide. It has been 2 days already and my precipitate is still green. Why do you think this is?

I’m really confused, please someone help.

Thanks
Brumer