Iframe src JS is not loaded when using no referer or filled referrer

Working on the porting of an ADDON to FF46:
I’m injecting some content script which creates an iframe and sets the iframe.src to an html file included in the addon. This html file contains a js script which should be executed at that time.
If I set src="/frames/frame.html?referrer=truereferrer", the included script does NOT get activated.
If I set src="/frames/frame.html" (no referrer tag) the script does NOT get activated
If I set src="/frames/frame.html?referrer=" (blank) the script DOES get activated

This is systematic and I reproduce the issue with a one line dummy JS.
Anybody has an idea if this is a bug, a CSP issue … ? I’m using the beta version FF46.