When inspecting the block states for crops and anything else that grows over time, it can be seen that this calue is stored in the "age" block state. However, navigating to the textures/block or models/block files in the jar's assets reveals that each of these iterations is named "stage" instead, which does not seem consistent at all.

To fix this inconsistency I'd recommend renaming the resources to use "age" instead, due to it being shorter and also more descriptive of what the block in question is actually doing.