Item with inventory(like bag), updating item issue

Hello everyone!

I have trouble with setting up item that has inventory, I want the inventory(currently one item) to be stored in tag compound of mobile phone(the item that has inventory)

Mobile phone also has ID stored in it's NBT tag.

I open GUI, insert SIM to the phone, on console I see that it's properly saving the card to the NBT, but in players inventory, on mobile tooltip it says "No SIM card". I found that if I force the mobile to update in players inventory, like that:

player.inventory.mainInventory[player.inventory.currentItem] = mobile;

It's working, but it also is a BUG dup-bug, so it can't work like that. What's the proper way of doing something like that?

My code:

Item Mobile(there are all NBT storing functions):

https://github.com/grabie2/mod_mobile/blob/master/common/grabie2/minceraft/mobile/item/ItemMobile.java

GUI handlers:

Client: https://github.com/grabie2/mod_mobile/blob/master/common/grabie2/minceraft/mobile/core/proxy/ClientProxy.java

Server: https://github.com/grabie2/mod_mobile/blob/master/common/grabie2/minceraft/mobile/core/proxy/CommonProxy.java

Mobile inventory:

https://github.com/grabie2/mod_mobile/blob/master/common/grabie2/minceraft/mobile/tileentity/container/InventoryMobile.java

Thanks for your help and time!

EDIT:

I saw that pahimar in ee3 saves NBT flag on his item when opening GUI and he looks for item with this flag set, does his work on this item and removes flag, but what if item is dropped?