Instagram URL is converted into oEmbed

Figured it out.

Embed shortcode stores the oemebd data as post meta using md5 hash.

wp-includes/class-wp-embed.php

// Check for a cached result (stored in the post meta)
$key_suffix = md5( $url . serialize( $attr ) );
$cachekey = '_oembed_' . $key_suffix;
$cachekey_time="_oembed_time_" . $key_suffix;

And has a cache mechanism to fetch new data only after a day.

I deleted the post meta and then it started working.