I received a Houfy booking but it did not update on my VRBO calendar.

On Houfy, go to Manage Listings, open the listing and click Calendar. Click Export in the toolbar (the up-arrow icon; on a narrow screen the word is hidden and only the icon shows).

Pick a tab. Houfy Reservations gives a feed of this listing's Houfy bookings only. Master Calendar gives everything Houfy holds for the listing, including dates it brought in from other platforms. To send VRBO only your Houfy bookings, use Houfy Reservations.

Copy the whole URL, then import it on the property's calendar in VRBO. VRBO changes these screens, so check VRBO's own help for the current path.

About timing

VRBO and Airbnb re-read imported calendars on their own schedule, usually a few hours. Nothing on Houfy can speed that up - the Sync now button refreshes calendars Houfy pulls in from other sites, and does not push your Houfy bookings out.

Because of that gap the same dates can be booked twice across platforms. If you sell on several sites, block the dates manually straight after a booking rather than waiting for the sync.