It might be that your account has some restrictions or violations. Instagram has certain rules, and if you've violated them, sharing might be disabled. Or, there could be a problem with the content you're trying to share, like it being against their community guidelines.
It might be due to privacy settings. If the person who created the story has strict privacy settings, sharing might be disabled. Also, check your own Instagram settings. There could be some glitches in your device that are preventing sharing. Try restarting your device and see if that helps.
One simple reason could be that the post format is not compatible with Insta story. For instance, some very large or complex video formats might not be supported for sharing as a story. Additionally, if you are using a third - party app to view the post and it doesn't have proper integration with Instagram's sharing features, you won't be able to share it to your story.
There could be a few reasons. Maybe your friends don't have the latest version of Instagram. Or, your account settings might have some privacy restrictions that prevent sharing. It's also possible that they just aren't familiar with the sharing functionality.
It could be that your internet connection is unstable. Check your Wi-Fi or mobile data to make sure it's working properly. Also, make sure you have the latest version of Instagram installed.
It could be that your internet connection is unstable. Make sure you have a strong and reliable connection. Also, check if Instagram has updated its sharing policies or if there are any restrictions on the type of post you're trying to share.