There is code of container in my mod: https://github.com/128-bit-guy/red-dpn/blob/master/src/main/java/_128_bit_guy/red_dpn/common/container/ExpNodeStorageContainer.java
If i will open my block entity from two accounts, and put item into slot from one of them, it will properly appear in gui of other account. Then, if i will take item from slot using second account, it won't disappear from slot in container of first account.
Maybe this is problem of my block entity / container, but i think this is problew with LBA's SlotFixedItemInv