Yes, the inventory is bugged. We are aware of it and we'll try to make a fix for it, as that's what we are trying for the few past days.
Until we manage to do that, here are some tips for you.
You did NOT lose your items!
They are still there, they just don't display in YOUR inventory menu. That's why you can't pick up more items - your inventory may be full though nothing is displayed.
Well, that sucks.
Yes, it does. But, you can make the item re-appear by dropping it and picking it up again. You drop it with chat command "/InvAction drop itemname".
Please be patient and don't bother us about this problem.