Facebook made a change in May 2021 : The Groups API allows going back only 90 days in time to gather the posts from a group. This is the reason we stopped providing the History product (getting the complete data history from a group).
While introducing this change, some users experienced an issue while adding the groups to Grytics : only data starting from the moment they added the Grytics app to the group was available (and not the last 90 days of data).
The bug was reported to Facebook and an answer was finally provided, 3 months after submission.
According to the Facebook team, this was not a bug but a new limitation due to the CCPA (California Consumer Privacy Act) : an app can only access group posts published after the app was installed on the group (https://developers.facebook.com/docs/groups-api/#limitations)
As of now, it seems that this behavior is applying to all Facebook groups (before it happened randomly). This change ONLY applies to Facebook groups, not to other communities Grytics handles.
Taking into account this new limitation, we have updated our service and we are sorry for this inconvenience.
We will keep you updated if there is any change to this.