Meeting request updates from a group calendar won't show up in the group's member calendar

Hello!

I have had this trouble since December, and I have asked my company IT team but to no avail.

I am a member of a certain group mail (e.g. xdept group mail) and periodically send meeting invites for attendees outside the group (as req. atendee) and cc (opt. attendee) the group mail (e.g. xdept) so the members of the group will have the meeting scheduled in their calendar.

for example : 

  sender: "xdept_at_aaa_dot_com"

  req. attendee: "abe_at_aaa_dot_com"; "bea_at_aaa_dot_com"; "cee_at_aaa_dot_com"

  opt. attendee: "dea_at_aaa_dot_com"; "xdept_at_aaa_dot_com"

For these two months, when I send/update a meeting request, it will show up with no problem for the attendees, but it won't show up in the group's members' calendars including mine (doesn't even show up in my/their inboxes). 

I changed my PC (hardware) and it was fixed for a short of time but then the same symptom re-occurring when I organize a new meeting.

What is extra odd is that when sending an email (not meeting invite), there will be no problem cc-ing the group mail (e.g xdept), and this symptom is not occurring in my another group mail (e.g. ydiv).

It's really frustrating, could anyone help me?

Thank you in advance.

Muthi