There are times that a song does not appear in the Instagram Music search engine, and this can be due to different reasons:
Option 1: If it is a search engine problem or the account is a business account
Posible problems
The song name and artist offer many similar results.
The Instagram account is a business account, and only allows you to use certain songs.
Solution
The good thing is that there is a simple solution to find these songs, we simply have to enter the following in the Instagram Music search engine:
isrc: + the ISRC code of the song
Example: isrc:PYC842301815
The only result on Instagram Music will be the song with that ISRC code.
Option 2: If it is a problem with the availability of the song
Posible problems
Failed to deliver release/song to Meta.
The song conflicts with another song in Meta's catalog.
Solution
Contact support to have a Random Sounds representative manually verify the issue in Meta. The release may need to be redistributed.