Offline Music

_harshrj,

Are you signed in with the Apple ID you purchased the content with? If not you'll want to sign in with that account to authorize your device. You can learn more about that here: Authorize or deauthorize your computer for iTunes Store purchases

Take care .

Hey there _harshrj,

Thanks for reaching out to Apple Support Communities. We're happy to provide some assistance.

Does this occur with all songs or this specific songs? Was anything updated or changed when this started occurring? This can help us isolate this issue.

Also, let's make sure your device is up-to-date. If it is updated, let's restart your device. Restarting your device and making sure it is updated can resolve many unexpected issues. 

Take a look here on how to restart your iPhone: Restart your iPhone

Take a look here on how you can update your iPhone: Update your iPhone, iPad, or iPod touch

Keep us posted.

Have a great day!