Hi PY,
Sorry for my confusion and therefore throwing you off here - my reply before seemed to be missing the word "alone" in terms of if it wasn't working for you based on file type alone, that the steps here were good ones to check through. The vector images are supported in Flash - but not HTML5 or AMP as per the documentation.
Taking a look a few of the images shared here (as I didn't have a way to create any of those file types myself) I can see that some behave better than others. I can't say with specificity why, as I didn't create them and the image files are not my specialty - but take a look at the two different camel images shared on page 1. The first one doesn't scale or work as expected once inserted - but the second one does. I'd suggest to go back and look at your images and how they were created using some of the feedback here to ensure they were set up to be vectored and able to scale.
Hope that helps clarify and feel free to let me know if you need anything else.