I wrote a bug report the other day about it and I believe I was told it wasn't a bug. I have since encountered that the floor of the greenhouse also changes based on the greenhouse, like the base.
As i am a programmer, and so are my friends, we all came to the conclusion that the blocks that a greenhouse is supposed to check are 1 block below than it is actually meant to be in the Y level direction, which is why we have the floor changing AND the blocks 1 below from the glass ceiling not changing. So it may just be a simple +1 in the source code. But I would let you know
I wrote a bug report the other day about it and I believe I was told it wasn't a bug. I have since encountered that the floor of the greenhouse also changes based on the greenhouse, like the base.
As i am a programmer, and so are my friends, we all came to the conclusion that the blocks that a greenhouse is supposed to check are 1 block below than it is actually meant to be in the Y level direction, which is why we have the floor changing AND the blocks 1 below from the glass ceiling not changing. So it may just be a simple +1 in the source code. But I would let you know