Hi Alan,
I just tried this on my iPad and it worked fine. (though my iPad is quite old so it's possible that there's a problem with newer ones?)
It also works fine on my Mac in various browsers, and PC browsers.
So, I'm afraid I have no great ideas here. Does anyone else have this same problem?
Updating the WYSIWYG to something more modern is on the To Do List, so there's a reasonable chance that when this update comes that editing will work better across more tablet devices.
Thanks
Joe