This is a bit more serious than I thought as I am using X themes Cornerstone editor. Page name keeps flipping back to some strange format (not even a default setting) i.e ‘page name-random number’. It loses the page setup for the page I am editing – i.e. reverts to default and not the Blank Container | Header Footer template.
Same problem. WP 4.3.1 keeps enforcing a -3 suffix on page names – no name conflicts anywhere is the first page added.
They broke it – not a good release.