Not sure if this is relevant to your issue, but if you are on the free plan, you can share one prototype only.
Thank you for reaching out. We're sorry to hear you're facing trouble creating a public link. We'd request you to please share the Adobe ID with me over a private message so that I can check your account.
Please send the URL of this forum post for reference. To send a private message, click my profile picture and use the Message button.
Please let me know if you face any issues with this. We'd be happy to help.
I'm facing the same issue, please advice
Just to be sure, are you subscribed to Adobe XD or are you on the starter plan? If you are on the starter plan, you are allowed to share one prototype at a time. However, if you are subscribed to XD, and are facing this issue, I suggest getting in touch with us using this link https://adobe.ly/2WYE62m
I was facing the same issue.
However, there was an update pending.
I updated the app and it worked fine.