I paused the game and when I unpaused it, all of my inventory was missing including my armour and the map in my offhand slot
MCPE-177761
Missing inventory
Resolved
Duplicate
0
AlexWhite
(Unassigned)
Unconfirmed
Nintendo Switch
Nintendo Switch Lite
1.20.51 Hotfix
Retrieved
Pausing the game doesn't actually pause it (see MCPE-21221), so it is very likely that you were killed by a mob and your items despawned.