oEmbed in wordpress multisite not working

We've multisite on single wordpress installation. For example,

Main site - testsite.com/

Sub site - testsite.com/subsite

Now when I try to embed a blog from subsite into mainsite or vice verca or post of subsite into subsite, it gives the error Sorry, this content could not be embedded.

Also when I see network call I see this error response,

{code:oembed_invalid_url,message:Not Found,data:{status:404}}

This is how I'm embedding a blog from subsite.

I'm not sure what I'm doing wrong.

Thank you!