adding a simple FB tab. works well with one url but shows blank page with another. Both are the same, both are HTTPS.
- https://www.chirva.com/stuff/ - works
- https://www.mchelper.com/fb_contact/ - returns blank page
both have identical settings on FB side. Same tab/canvas details (only URLs are different). Can it be on hoster's side? (something like "protected from embedding" )
Please have a look at a test page where I tried to embed both URLs http://a5w.org/mch/ as you can see - the first one won't load. why???