When setting up a group, you define an allocation drop date—this is the date when any unpicked rooms are released from the group block and returned to general inventory.
If you see this message, it means the drop date has already passed, and as a result, you can't make changes to the group allocation. This includes modifications like changing room types or adding more rooms, even for reservations that were already picked up.
To make changes, you’ll need to reopen the allocation by updating the drop date to a future date. You can also adjust the drop setting from “Arrival Date” to “Departure Date,” depending on your needs.