i just reported the exact same issue. This is making the game unplayable. The server seems to register everything i do (interaction with items and such) however you'll only find out if you log out and back in. Btw i'm not carrying backpacks within my backpack. However i do have a couple of medkits and yellow protector cases inside my inventory.

http://feedback.dayzgame.com/view.php?id=6337

hmmm i can't even find a full server... will try and report back.

Just tried this and i confirm the issue goes away with a full-ish server. However it seems strange to me that you are unable to play on a server with just a few people on it.

And the issue is back. Even when i see the yellow chain i'm unable to use the hotbar or anything in my inventory.

just reported the same issue. http://feedback.dayzgame.com/view.php?id=6337

correction the game is not even in beta, it's in alpha. However the same thing happend here too a few times