Hi Ian,
That button literally doesn’t exist on my main account. But, when I logged into the account I gave you it showed up?
If this is the case, it may be user account privilege related.
Or perhaps, page-caching.
As for the first point, you may have to contact LearnDash’s support about it.
As for the page-caching, you’ll have to check for any plugin that does this. You may also have to check on the hosting’s cpanel if they have this feature.
A wise man once said:
"Have you cleared your cache?"