Thanks @sietsko – this was one of those rare WTFF moments and had rolled back to 3.6.12 across all my sites.
Much appreciated – 3.6.13 now installed and sites working fine – awesome work !!!
Basically, the fix is to delete the plugin and re-download and that seems to have sorted the problem. Apologies to the author who did respond to an earlier support request 3 week back which I hadn’t spotted and suggested this fix 🙂
