If you are using iCals to bring in bookings from Airbnb, booking.com, VRBO etc and you see the external booking has changed and lost any data you manually added, it's because Cancellation & Amendment is switched on
Head over to Configuration > Channel Management > iCal Feeds
The first toggle (red means ON, grey is OFF) indicates whether your account is listening to Amendments and Cancellations within the iCal feed.
The originating booking will drop off the iCal feed naturally when a change occurs by the third party. Anytime will move any booking no longer in the iCal feed to the cancelled bookings.
If you want to store notes or general information on a guest on an iCal booking, we would recommend turning off this feature.
With this feature OFF, Anytime won't know if the booking was cancelled or amended at source. Remember to manually update the booking manually to reflect those changes. 
TIP: If you want to find any stored notes you had saved on the booking when you had this feature ON for a period of time. You can find the originating old amended or cancelled iCal bookings within your Cancelled Bookings List.