After logging into a server, I noticed that all of container-items laying on floor (medkits, barrels, clothings) doesn't show up in my TAB menu. I tried it with lots of stuff from Cherno to Elektro - there were no problems with regular loot, but everything that could act as container didn't show up in TAB menu, I couldn't put them in hands, and in fact it looked just like a simple model lying on floor. After I relogged, everything was fine.