Amazon Native Shopping Ads

My site launched last wednesday after almost two years of writing, editing and technical development. Began to ad Amazon contextual advertising at bottom of selected pages. I use Visual Composer but switched over to the text/html editor and pasted ad code at the bottom. Shows great on page view BUT if you go into visual editor to do anything, the code disappears from html editor. What is going on? How else do you insert them. I called Amazon and they were totally clueless. Thanks.

Mark