oEmbed in wordpress multisite not working

Question

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!