If you switch your item that you're holding while breaking a block, the block breaking restarts. But if you're punching with your fist, and you switch to another empty slot, it goes as normal.
Linked issues
Comments 1
MC-17633
Item Switch while Breaking Block Glitch
Resolved
Duplicate
0
iamanai
(Unassigned)
Unconfirmed
block, item
Snapshot 13w23b
Retrieved
Duplicate of MC-2519, please use the search function to see if your bug has already been submitted. Currently over 57% of tickets are being closed as duplicate.