[Multiplayer Only] Leaves Glitch

So, I am working on this tree on my Minecraft Server. When I select leaves (any kind) with the new "Select Block" feature (Button 3), they turn into Oak Leaves.
It's not only that, the same thing happens when I use the inventory leaves! I just select them, and the moment I put them in my Hotbar, they turn to Oak Leaves (just the name, of course). But that's it.
I've attached two images. One shows the leaves when I Button3 them, and the other shows the ones that I've dragged in my Hotbar.