Suffocating despawn items

I was in a multiplayer world strip mining then I start getting low hunger at that point I had an lot of items so I thought I suffocate myself to respawn and get my items so I did it with gravel after I died I came back down only my armor and my shield was there so I thought oh it behind the wall there was water but none of my items so I start getting scard that 3hr of mining was gone I look everywhere and it wasn't there and I know it didn't despawn because I killed myself and went back down in less then a minute I decided to stop playing I was disappointed that all of my things was gone and knowing that bug or something there makes my scard of it happening again so I play with keep inventory but the problem with that Is that I get no achievements I hope this get fix or someone tell me what really happend

I was in a multiplayer world strip mining then I start getting low hunger at that point I had an lot of items so I thought I suffocate myself to respawn and get my items so I did it with gravel after I died I came back down only my armor and my shield was there so I thought oh it behind the wall there was water but none of my items so I start getting scard that 3hr of mining was gone I look everywhere and it wasn't there and I know it didn't despawn because I killed myself and went back down in less then a minute I decided to stop playing I was disappointed that all of my things was gone and knowing that bug or something there makes my scard of it happening again so I play with keep inventory but the problem with that Is that I get no achievements I hope this get fix or someone tell me what really happend

Was in beta 1.16.62 time:9:20

I was in a multiplayer world strip mining then I start getting low hunger at that point I had an lot of items so I thought I suffocate myself to respawn and get my items so I did it with gravel after I died I came back down only my armor and my shield was there so I thought oh it behind the wall there was water but none of my items so I start getting scard that 3hr of mining was gone I look everywhere and it wasn't there and I know it didn't despawn because I killed myself and went back down in less then a minute I decided to stop playing I was disappointed that all of my things was gone and knowing that bug or something there makes my scard of it happening again so I play with keep inventory but the problem with that Is that I get no achievements I hope this get fix or someone tell me what really happend

Was in beta 1.16.62 time:9:20

I was in a multiplayer world strip mining then I start getting low hunger at that point I had an lot of items so I thought I suffocate myself to respawn and get my items so I did it with gravel after I died I came back down only my armor and my shield was there so I thought oh it behind the wall there was water but none of my items so I start getting scard that 3hr of mining was gone I look everywhere and it wasn't there and I know it didn't despawn because I killed myself and went back down in less then a minute I decided to stop playing I was disappointed that all of my things was gone and knowing that bug or something there makes my scard of it happening again so I play with keep inventory but the problem with that Is that I get no achievements I hope this get fix or someone tell me what really happend

Was in beta 1.16.61 time:9:20