I recently upgraded from 4.0.1 to 6.2.3 and I've installed AOS Modules (Advanced Open Sales). When I try to put these modules under a grouped tab, Invoices, PDF Templates, Quotes and Products and displayed as I wish, but the Contracts module is just not displayed. I can add it under a grouped module, but when i click on Save & deploy, it is removed from the grouped tab.

Does anyone has got this issue and is there an easy fix?

Thanks