No diamonds at Y coordinates 12 but there are emeralds which would be expected at a higher y coordinates.

I am at Y coordinates 12 and I am not getting diamonds but have already got 8 emeralds.

What I expected to happen was...:
I thought I should get more diamonds at that level.

What actually happened was...:
No diamonds and 8 emeralds

Steps to Reproduce:
1.Just go to Y coordinates 12 and mine

2. I mind for 5 hours and got 1 diamond and 8 emeralds

3. All other resources were of expected quantities.

4. I was playing on Windows 10

5. My wife was playing on XBOX One and got only 10 diamonds