game version 1.20.1
forge version 43.7.22
mod version 9.1.24

Bug description：
During the game, the Tanks upgrade on the backpack suddenly disappeared，No obvious reproduction method has been found for this bug yet

Need reproduction steps for this, never happened for me

Same is happening me for me. The issue is the last slot specifically I believe, happens with all upgrades. Open a netherite backpack with 5/6 upgrade slots filled. Place a 6th upgrade in the last slot, then reopen your inventory. The final upgrade disappears.

Screenshot of my inventory when this happens

(I know this is off topic, but since i'm here, does anyone happen to know which mod is adding those sorting icons to the top right? Want to see if I can find a way to disable it in this GUI)

Is there a chance youve updated the mod from previous alpha like 9.1.22 etc.?

There was a bug like that in previous version, but I'm pretty sure I've fixed it, I can't reproduce this either
@ErikDombi I'd be glad if the bug can be reproduced on the newly crafted backpack and upgraded to netherite tier. Of course if you use 9.1.24, if not please update before checking it

There was a bug like that in previous version, but I'm pretty sure I've fixed it, I can't reproduce this either @ErikDombi I'd be glad if the bug can be reproduced on the newly crafted backpack and upgraded to netherite tier. Of course if you use 9.1.24, if not please update before checking it

I found that he proposed a fix for this bug.Only the netherite backpack is not carried on the back. Put the upgrade module in the last slot, close the backpack and open it again, and the upgrade module will disappear.

I'm on 9.1.24 and i'm able to reproduce. Some extra information, I have the Fox's backpack in a "back" slot, and i'm running 1.20.1 Forge. Server and client are both updated.

If you need an environment where you can reproduce, please send me a message on discord ("wickedlizerd"). I can provide you with my server IP and any relevant logs you may need. I know it's nothing like having a debugger but it's something.

@ErikDombi Sent friend request

@chessMCman
This issue has been resolved and all newly crafted will work properly. All previous backpack might be affected with this bug.
Please do the following to the backpack you experience the issue with:

1. Empty your backpack (remove all tools, items and upgrades)
2. Place it on the ground
3. Shift + Right Click while holding Blank Upgrade (It will reset your backpack tier upgrades)
4. Re-apply tier upgrades
5. Issue will not occur again