I've had this occur a few times now and I'm not sure what's going on. I am the owner/admin on my server, and today when I logged in I cannot access my backpack. When I click on it or uset he keybind the backpack opens but immediately closes again. I can't put anything into or out of the backpack. Other suers are able to use theirs just fine, it's only the admin. It's not a permissions issue, I have access and the backpack does open, it just closes agina before I can do anything. The server just reset half an hour ago, I reloaded my game and my Steam, and I reloaded the plugin. I tried going into a comtainer and out as suggested in another post, but nothing has worked. I've had this happen before and the problem just seems to go away on its own and recur again from time to time and I don't know why.

When you click the backpack button, are you doing that from your inventory or are you opening the chat window in order to get the mouse cursor? Additionally, is your key bind use the chat command (chat.say /backpack) or console command (backpack.open). Asking about chat because there has been an issue before where if you use chat to open the backpack, if the chat window closes too slowly (due to client side lag for example), it can cause the loot panel to close at the same time. The plugin currently tries to mitigate this by adding a short delay before opening the backpack in cases where it's not possible to know whether chat was open.

I still use the key binding for b to open the backpack and have never had any problems with it.

Nothing worked. But I tracked down the issue. I am using RealPVE, and if I use the command for that plugin for myself to override restrictions so I can open boxes and TCs of players, that's when the problem occurs. If I turn off the admin override I can access my backpack again.