I've tried planting the seeds at multiple elevations to see what happens.

Ground level: Did not even let me plant the seed on farmland. I assume this is working exactly as intended.

Y 108: Could plant the seed. Can bonemeal it, but it never advances its growth.

Y 140: Same as y 108, it can be planted and bonemealed but it never advances past growth stage 0

The 'age' stays at 0 even after waiting a while or applying bonemeal.

most definitely a bug, I was checking with the wrong kind of light method.

now it works as intended -- to have a greater chance of growing the higher up above 100y it is