Blocks disappear after changing their place with digits.

Blocks disappear after changing their place with the digits.

What I expected to happen was...:
Block 'x' should go to place 3 in the inventory bar after pressing '3' while standing with the cursor on the block.

What actually happened was...:
Block 'x' disappeared and never came back. :/

Steps to Reproduce:
1. Place blocks in your inventory bar.
2. Hold the cursor on a block.
3. Press any number (1-9) to swap places  .                                                                                      4. Block glitches and disappears.