Falling destroys entire inventory

I was in a Realm:

 

I was entering a mineshaft i had dug down to Y-12 and i missed my ladder and fell all the way down and despite have diamond feather falling boots i somehow died. My ENTIRE inventory was completely deleted instead of dropped the only items i was able to retrieve was the armor i was wearing. I lost a perfect enchanted diamond pick and an entire inventory of materials i had spent HOURS carefully harvesting for a construction project. Needless to say i’m fucking pissed and questioning whether or not to continue playing a game that so easily destroys your hard work.