Shulker boxes disappear when mined in singleplayer

We do not have enough information to find the cause of this issue.

Please record a video of this happening and attach it to this report.
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_{This issue is being temporarily resolved as Awaiting Response. Once the requested information has been delivered, the report will be reopened automatically.}

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Sure, here is a video

You didn't attach it here, it's broken.

I am not sure why it did not attach the first or second time. But here we go again.

I have tried everything, but it seems to be an issue with the game itself as even after removing and resource packs, the issue is there.

I have also tried this in vanilla and the same is happening. Here is a clip of the same!

Also, don't just dismiss the concern if the version is a little modified as it is optifine only and no other heavy mods.

Do you have any outdated data packs? Is /gamerule doTileDrops set to true?

I have never tinkered with the game rule and not sure about its status. However, I did see that I had a data pack which was for version 1.16. After deleting it, the issue seems to have resolved. 

I will keep an eye out just in case and will share any findings here if the issue reappears. 

Please consider this issue as resolved for now.

Thanks for your assistance!