It could be that your account settings are restricting the sharing feature. Check your privacy and sharing settings in Instagram to make sure everything is enabled correctly. Also, make sure the post you're trying to share is allowed for sharing to stories by the original poster.
If it's a technical issue, try updating the Instagram app to the latest version. Newer versions often fix bugs that could be causing the problem. Also, check your device's connection. Make sure you have a stable internet connection, either Wi - Fi or mobile data. If the problem persists, you might want to contact Instagram support for further assistance.
First, check the post's privacy settings. If it's private and not shareable, there's not much you can do. But if it's a public post, try refreshing the page. Sometimes a simple refresh can make the share button work. Also, make sure your Instagram app is up - to - date. Outdated versions may have bugs that prevent sharing.
There are multiple things you can do. You can check if your account is in good standing and not restricted in any way. If you've recently violated Instagram's community guidelines, your sharing abilities might be limited. Another thing to consider is the type of post. Some posts, like those with certain copyright - protected content, may not be shareable. If it's a regular post from a regular user and everything else seems fine, contact Instagram support for further assistance.