The Bug:

The pick block function doesn't find items held in the offhand.

Steps to Reproduce:

1. Obtain two stone blocks and switch to survival mode.
2. Place down one of the stone blocks and hold the remaining one in your offhand.
3. Use the pick block key while looking at the stone block you just placed.
4. Observe how the stone block in your offhand is not moved to your main hand.
5. Take note as to whether or not the pick block function doesn't find items held in the offhand.

Observed Behavior:

Items held in the offhand aren't found.

Expected Behavior:

Items held in the offhand would be found.