Hi Ian,
You have an wpautoterms-footer class element blocking the footer coming from a third party plugin.
It has z-index: 10000002; which is higher than the scroll to top button, causing it to overlay on top of it, effectively blocking it.
The quick and easy solution is by overriding this CSS with this:
.wpautoterms-footer {
z-index: 1;
}
But I’m not exactly sure if there’s a UI setting for this within the plugin. If there is one, it’s better to do it there. 😀