Doing a large family genogram with pictures added.  Some pictures when added look great but when saved and reopened some of the pictures are no longer visible.  Instead there is only a large red X.  How can I prevent that from happening?  What causes one picutre to remain a picture and another picture turns into a large red X when saved and reopened.

There is also the menu item Tools / Refresh Picture Properties which may or may not help here.