I think I am having the same bug. With the updated method of moving blocks (clicking the block in the existing slot then clicking on the destination slot) you can only move the whole stack, rather than choosing to move part of the stack. So, for example, if you have a stack of 64 planks in a chest and want to pick up 10 of them, it won't let you - you can only pick up all 64. I'm pretty sure this is what the OP was referring to.
I think I am having the same bug. With the updated method of moving blocks (clicking the block in the existing slot then clicking on the destination slot) you can only move the whole stack, rather than choosing to move part of the stack.
So, for example, if you have a stack of 64 planks in a chest and want to pick up 10 of them, it won't let you - you can only pick up all 64.
I'm pretty sure this is what the OP was referring to.