when you wear an invisibility potion in third person mode, when you swing your arm to hit something the item in hand doesnt move

i expected the tool in my hand, which was my daimond sword, to swing with my arm

what really happend was it stayed still while my arm moved

Steps to Reproduce:
1. drink an invisibility potion, (i used 8 minutes)
2. go into 3rd person mode
3. try to punch something with an item in hand