Dear Peter,
If you are a collaborator or the owner of the form, you should have the option by default.
After involving some resources, there seems to be no on-going Microsoft Forms related incidents currently. I'm afraid that you may let our related team help you fix the issue in your environment directly.
I kindly suggest you contact the administrator in your organization if you aren't the administrator and let him open a support ticket to our related team as soon as possible.
Sorry for that our category may have no enough resources on helping you fix the issue in your environment directly.
Thanks for your understanding and have a nice day!
Sincerely,
Cliff | Microsoft Community Moderator