The issue was found based on this topic (https://bugs.mojang.com/browse/MC-136506).
Bug happened when I placed the crafted item right back to the crafting table to craft another item, i.e.:
craft a redstone lamp in a crafting table
take the lamp from the output slot right back to the crafting table
4 redstone given from the function became ghosted
Please also refer to the video (https://youtu.be/s5mqqT48aHE).
Can confirm this is an issue still persisting on 1.13.2. Very annoying.