Signs do not seems to copy NBT data when I hold control and click pick block.

What I was expecting to happen was, when I hold control and click pick block, I will get a sign in my inventory, and when I place it down, it would read the same as when I copied it.

What actually happened was, when I held control, and clicked pick block, I received the sign, and when I hovered over it, it said it has NBT data, however when I placed it down, the message that I put on the sign that I copied it off of was not there, and instead it gave me the normal sign GUI. Even after typing nothing in that GUI, the original sign message did not pop up.

To replicate this first you need a sign, that you place down, and type whatever you want on it. Then you need to click done on the sign to put the message onto it. Afterwards, hold control and click pick-block facing it. Then hover over it, to see that it has NBT data. Then place it on the ground, and click done when the blank GUI comes up, and you will see that it did not copy.