Hi Kate,
This problem of image getting cut is encountered when the image size exceeds the maximum size that readers can support. For example, for iBooks it is 600 x 800 pixels; if it is larger the image will get cut.
You can try these alternatives:
1. Specify image size as Relative to text flow in EPUB export options dialog and then export.
OR
2. Reduce the image size in InDesign so that it is within 600 x 600 px.
Let me know whether the problem resolved or not.
Regards,
Pooja