Unknown if this happens through oak saplings, have not had a large oak generate through bone meal (thanks RNG)

Spruce saplings dropped by the hybrid tree grow into normal spruce.

I can confirm this issue. Actually have a large "pine oak" growing over my house in my main world.

I can confirm this, too...

The large green trees used in autumn woods biomes are vanilla the same vanilla tree generators used to generate the rare large trees in the game...this is vanilla code that has the leaf block and metadata hardcoded...yet in autumn woods biomes it used the spruce leaf texture. I can find no explanation for it, even after stepping through the code in the debugger.

I cannot fix the issue at this time, without replacing the tree gen with another.

Found the problem.

woo! what was the issue? I'm curious