Hi Michael,
This is a known issue. It only happens with Quick Meetings / Private URL Meetings.
It happens because:
1) A quick meeting is created when a new extension is created on your PBX and you login for the first time using this extension's credentials.
2) Since the Quick Meeting is a standard non-modifiable meeting, meaning you cannot edit the scheduled time this meeting is going to happen, the time this meeting is scheduled is the moment this extension was created/logged into the first time.
So when you invite someone to your Quick Meeting, since your Quick Meeting was created waaay in the past, this is the time/date the user you invited will see.
We will see in a future version how to approach and fix this.
For the moment however i would not expected a hotfix in 9.0.