Some vectors can't be visualized after I export to epub (fixed-layout)

[#1]

My epub works fine, but some vectors can't be visualized, instead it appears an "x"

[#2]

My epub works fine, but some vectors can't be visualized, instead it appears an "x"

[#3]

What is meant to be where the X is ? It looks like a close button icon... Can you share a screen grab of InDesign please ?

[#4]

This is my problem

[#5]

is the graphic a PNG file ?