VERSION

• FORGE: 40.1.85
• MINECRAFT: 1.18.2
• SC: [1.18.2] SecurityCraft v1.9.3.1.jar

NEED

• Briefcase
• any item
• another any item with high value

HOW TO REPRODUCE

• Create a briefcase (any password)
• put valuable item inside
• put other non-valuabe item in your hotbar (example: slot 2)
• place your mouse upside non-valuable item
• press the number where is located briefcase (example: slot 1 - press number 1)
• briefcase get switched slot
• now take briefcase with mouse (now its posible) and remove items from briefcase (interface keeps open)
• close interface menu and reopen briefcase
• now items are on briefcase and your inventory

DUPE SUCCESS.

VIDEO:

Thanks a lot! This was very clear to follow, making it easy to find the issue. It will be fixed in the next version of the mod.