Something is wrong with calendar groups

Something is wrong with calendar groups

Hi, I have multiple groups in my account and some users as members of those groups.

For some unknown reason, users are not automatically subscribed to the groups calendar's they belong to.

But if I create a new group right now, all the user that belong to it, are automatically subcribed to the group's calendar.

To summarise, 3 weeks ago created groups didn't auto subscribe their members to the groups calendar. New groups created right now, have it member subscribed to the groups calendar automatically.

Is there something wrong? I havetryed several things but I think there is a behavior or bug in calendar groups.
Thanks