There could be several reasons. Maybe the privacy settings of the feed post don't allow it. For example, if the post is set to be private only to a certain group, sharing it to a story might be restricted. Another possibility is a technical glitch in the app. Try closing and reopening the app to see if the option becomes available.
First, ensure your internet connection is stable. A weak or intermittent connection can prevent the post. Try switching from Wi - Fi to mobile data or vice versa.
First, check the privacy settings of the post. If it's set to private or restricted in some way, that could be the problem. Then, try refreshing the app. Sometimes a simple refresh can fix glitches. If that doesn't work, check your own account settings to make sure you have the appropriate sharing permissions.
One possible reason could be a technical glitch in the app. Maybe there's a problem with the app's server or an issue with your device's connection. Try restarting the app or your device.
There could be a number of reasons. Maybe your network connection is unstable, or the content you're trying to share doesn't meet the platform's guidelines. Also, sometimes there are temporary glitches in the system that prevent sharing.