If organizer changes time (which can be done by dragging the appointment around the calendar) of an instance before opening ResourceFinder (RF), Resource Central cannot know which instance is currently opened.
If he wants to change the order/resource and meeting time of that instance, he should open RF first then change the instance's order/resource. After finishing with those steps, he can change the instance's meeting time (via RF or Appointment window) and send update for that instance.
This has been confirmed as a defect and will be reviewed for a future release of the product.
Applies to: RC 3.8
Fixed in: Add-in 4.00.0084
Reference: TFS #23079
Knowledge base ID: 0158
Last updated: Feb 23, 2016