It could be that your account doesn't have the necessary permissions or your IGTV content doesn't meet the sharing criteria. Sometimes, it could also be a temporary issue with the platform.
There are multiple potential reasons. One is that your IGTV might not be fully processed or approved yet. Instagram may have certain checks and balances in place before allowing sharing to stories. Also, if you have a new account, there could be some limitations on sharing until your account gains more credibility. Additionally, if you have violated any of Instagram's community guidelines in the past, this could restrict your ability to share IGTV to story, even if the current IGTV content is compliant.
One reason could be that the IGTV video format is not compatible with the story format. Instagram has specific requirements for what can be shared to a story. The video might be too long or have a resolution that is not suitable for a story. Additionally, if your device has low storage or a slow internet connection, it could also prevent the sharing process.
The inability to share IGTV on story could be due to a variety of factors. Firstly, the owner of the IGTV may have disabled sharing options for that specific video. This could be for various reasons such as they only want it to be viewed directly on IGTV. Secondly, Instagram's rules and policies play a role. If the content of the IGTV violates any of Instagram's community guidelines, sharing on story will be blocked. Additionally, network issues can also cause problems. A weak or unstable connection might prevent the sharing function from working properly. Try to ensure you have a stable network connection and check if the video meets all of Instagram's requirements.
It might be that the specific IGTV video you're trying to share has some restrictions or is not compatible with being shared on stories. Also, ensure your app is up to date as older versions might have sharing issues.