I now can confirm, this problem appairs randomly on a lot of different sites. In Dolina for example, also at the three houses at the traintrack between Elektro and Cherno.

I, now, had the same issue in the military base near vybor. There was also a massiv loot spawn with dozen ak's. If you put one ak up a new one spawned in the next building. It was a amount of loot to, at least, fully equip 30 players with weapons, backpacks, ammo, food, uniforms, boots, helmets, short, everything. When i first got there i found, for example, 2 ak-101, 1 akm, 1 ak-74, 5 sks, 3 shotguns, 1 pumpgun, 2 winchesters, 5 ak-74u, 7 makarov, 3 cz-75, 1 p1, 3 crossbows, 1 blaze, 2 sporter and 3 cr527 carabines.

A clanmember of mine has found a workaround for this problem. If the inventoryscreen is opened and you can not pick up the item, just drag and drop it out of the inventory screen (just to the left). It is necessary that you put it outside the inventory screen. Drag and Drop in the inventory screen won't help. After you did it you can pick up the item like nothing is wrong.