The solution to this issue is very simple and trivial. The issue itself is a known problem in the community and many users experience it. Since Skype for Linux 4.3 is the newest available main version, uninstalling and reinstalling does not seem to help the problem.
In July 2016, Skype has introduced Skype Linux Alpha. Whilst this version seems to support group chats for users of various operating systems, it's alpha version still makes it unreliable if consistency is needed, e.g. professional purposes such as job interviews.
I have solved this problem by resolving to Skype's web version. Logging in with your account, enables the group conversation seamlessly, without the need to create a new group. Although group conversations are now possible, accepting an invite to share a screen does not seem to work herein.