White background appearing when exporting to EPUB

Hello!

Working in InDesign CC.

I am exporting a 45 page INDD file as a .EPUB. All placed images are exporting perfectly expect one - you can see the white box bordering the image below.

- I have tried every version of the placed image possible: .AI (original vector file), EPS, PNG, PSD, PDF.

- As I placed each file version I have made sure to check "Show Options" and confirm that any Transparent Background options where properly set. 

- I imagine I am missing a basic rule of placing images but am out of ideas!!!!!

Thank you in advance for any assistance.

- Jason