If you are experiencing any bugs, please contact the NS Support here for a solution.
The link above is the best option to see if the bug can be fixed.
You can still report a bug here if you want.
The only difference between posting here instead of contacting the NS Support is that I will confirm whether what you are experiencing is a bug or not.
If it is a bug, I will give you the same link above.
If it is not a bug, then I will give you a solution how to avoid that problem you are experiencing (problems such as inventory being full and etc.)