There are several reasons. Maybe your friend doesn't have the latest version of the app, or there could be a problem with their account. Sometimes, server issues can also prevent them from seeing your snaps.
It could be that your friend has blocked you accidentally or there's a problem with their internet connection. Also, make sure your story is set to public or visible to your friend specifically.
There could be several reasons. Maybe you've restricted their access accidentally in your privacy settings. Check if you've set the story to be visible only to a certain group and excluded them. Another possibility is that there's a glitch in the app. Try logging out and logging back in.
There's a chance your friend removed you from the list of people allowed to see their story. Or, it might be that the story has expired and is no longer available for viewing.
Check your privacy settings. Make sure you haven't accidentally set the story to be private from your friend. If that's okay, ask your friend to check their app settings or reinstall the app in case there's a problem on their end.
There could be a few reasons. It could be that you're not on their approved list of viewers. Or perhaps there's a technical issue with your Snap app or their account settings.