As the question states. I know it's definitely possible because I have a file that works. However I cannot replicate this. Here is the warning I get when I try to export.
The file was exported but one or more problems were detected:
Custom Layout settings in Object Export Options have not been honored for group children and inline objects.
Inline objects like text frames, groups etc. have been rasterized.
You change it to an Above Line graphic. To understand why, read this document on the changes in handling EPUB between 9.0 and 9.2:
Look at the section beginning on page 11 in the PDF file in the Anchored Objects section.
Omg, thank you so much. This was giving me so much trouble.