If it's a technical issue on Instagram's end, there's not much you can do except wait. However, you can try some basic troubleshooting steps on your device. For example, close all other running apps to free up memory. Also, as mentioned before, clearing the Instagram app's cache can be helpful. If the problem persists, consider uninstalling and reinstalling the Instagram app, but be aware that this may cause you to lose some local data associated with the app.
It could be that your IG app is outdated. Update the app to the latest version and check again. Also, make sure you haven't violated any of IG's posting rules.
There could be several reasons. Maybe your internet connection is poor. Check your Wi - Fi or mobile data. Also, it might be due to a problem with the Instagram app itself. Try updating it to the latest version.
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 Outdated versions may have bugs that prevent sharing.
It might be due to a storage problem on your device. If your device is full and there's no space for the IG story to be saved temporarily while uploading, it won't post. Try freeing up some space. Or, there could be a glitch in the Instagram app itself. Try closing the app completely and reopening it.