Shulker boxes still disappear and delete items

Shulker box issue

Instant 1

So me and my friends play on a server together, as i one of  them died i had to pickup his items so i pulled out one of my shulker boxes and placed all my items in so i could pick up his items, after i got all of his items inside a shulker box i went back to my shulker box (placed on the ground) all but like 5 items had been deleted, this was pretty heart breaking as i had played a lot to get those items.

Instant 2

i went to the end as i was going to make a enderman farm, i placed some water as i was going down under the main island, before i did that i made sure to place all the things i had on me in 3 shulker boxes so if i died i could get my items back, so after i went under the main island in the end and died i was not really that worried as i had all my items in the 3 shulker boxes, after i came back the shulker boxes where gone with all the my hard earned loot inside as my maxed out elytra ect.

 

This is a pretty bad and game breaking bug as i now have to start for the most part over again and i can't trust shulker boxes to hold my items as they might delete items or disappear when placing limiting my inventory.

I have not found a fix or anyway to get items back (unless i cheat) 

-Liartago