Currently only meetings booked through Concierge can be manually synced to HubSpot if the initial meeting creation failed (through the Concierge logs). If the meeting is not created for a meeting booked with a scheduling link (or Handoff, but we aren't currently using this), there is no way to push a sync to HubSpot for that meeting. If I remember correctly, this was possible for all meetings on the old platform since it was an option when viewing the meeting record.