A loaded crossbow in the offhand can cause the mainhand to be invisible if it's empty
MC-208604
While the mainhand is empty and there's a loaded crossbow in the offhand, the mainhand will appear invisible
Resolved
Fixed
7
Confirmed
Important
Player Animation
20w51a, 21w03a, 21w05a, 21w05b, 21w06a, ..., 21w14a, 21w16a, 21w17a, 21w19a, 21w20a
1.17 Pre-release 1
Retrieved
Prior to the 1.17 snapshots, the crossbow would render as if it was in the main hand, which probably is the desired behaviour and the reason for the hand disappearing.