Leaves are now solid blocks.

IGN: Angus_Glowsong
It looks like after OR's update to 1.20 custom leaves (Wisteria leaves and flowers at least) are considered solid blocks by the game. (Which is really annoying to me, since my storage is decorated with wisteria leaves at the top and so I can't open around a third of my chests.)

I have found where to report bugs! :D