Moved to InDesign EPUB forum.
Switch the anchoring option to custom or above line for the image. This should work.
I'm not sure where the anchoring option is?
Thanks but seems a bit different to my problem where images are splitting onto the next page, not just cutting off.
I'll keep trying different options in object export etc.
In InDesign, select the image and go to:
Object > Anchored object > Options
(and if you mainly target iBooks on iPad with full screen images, be careful ot to use a use an aspect ratio greater than 3/4.)