0. ALWAYS PROVIDE INFORMATION ABOUT MODLOADER (Fabric / Forge) AND MOD VERSION (For Example 1.19.2-8.2.10) prism forge 1.20.1 travelers backpack 9.1.30

1. Describe the bug
   i will put an item in my backpack, and when i reopen it its gone
   this is happening with any tier with backpacks opened from the hotbar, my equipped diamond backpack is functioning normally for now

2. Write steps to reproduce the bug
   put an item in a backpack and open it again

3. What is expected behaviour
   items disappear

4. Screenshots (If applicable)

zambie modpack.zip

And what exactly version of the mod you use? Fabric/Forge?

Do you play on curseforge launcher maybe? So you could share profile code with me and I could check that? I think there's mod compatibility issue because I can't reproduce this

Do you have backpack upgraded to higher tier?

Did you update from previous version?

Did you update from previous version?

I was using an older version originally, then the issue stared happening so I updated and it’s still going on.if the backpack is equipped it works fine but using it from the hotbar causes this

Do you have backpack upgraded to higher tier?

My equipped backpack is a diamond tier creeper backpack, the hotbar backpack is normal with iron tier. If I equip the normal backpack the issue is resolved until I unequip it again

And what exactly version of the mod you use? Fabric/Forge?

I am on prism launcher with a forge 1.20.1 travelers backpack 9.1.30 version of the mod. In the original issue message I attached the mod pack I am using. if you have prism you could maybe join my world with essential and test there

Tested with all mods provided on singleplayer bug does not occur