Shulker box disappearing

Hello, Im continually experiencing problem with shulker boxex. I put them on ground.. put things in them and then mine them with pickax a and puff... sometimes they are gone. And NOW I had 4 shulker boxes on ground picked them and only 3 of them.. so I pressed Alt F4 for not to save.. and reload the game and  i have only one noe. So I lost 3 of them in just 10 mins. I experienced this multiple times and my friend also - on pc and swith when we played together.
I just lost about 4 hours of playtime because of this.
Is there any solution? I found some ppl complaining about this almost 2-3 years ago..