I have reasons to believe some of the thumbnails of previous activity had been deleted. Is their anyway to retrieve deleted thumbnails?
Is their any way to find out what other users may have accessed the cameras?
If you have shared the camera and access rights to the saved footage you can see bow many times and when last the camera was accessed.
If no other user has shared access there isnt a way of knowing.
If you have sd card storage deleting th thumbnail doesn’t delete the saved sd card storage. It hits deletes the notification