Display Issues

Ok i have searched the forum and can’t see this anywhere else but i cannot believe this is the first time this has appeared.

When I add video embed code or shortcodes for pugins to a post they never appear on the homepage, just mangled looking code, however clicking through to the actual post pages everything works just fine.

My theme has not been butchered and no plugins are running except the one for the shortcode, no matter what shortcode plugin i use (each tried in isolation) the same thing happens.

Anyone help me with this frustrating problem?

Thank you in advance
T