Upon checking your 2 sites.
Your about page on both sites is not editable if Convertplus is active.
Once we de-activate it the page works.
It is known bug we found a couple of days ago and we can replicate on our own installations.
I understand you might be frustrated but at the moment we have to search for a workaround.
We have suggested you a couple of ways, I understand they are far from ideal, but as I mentioned we are working with the plugin developer to fix the issue and we cannot do anything about right now.