Still no joy Im afraid.
Have uninstalled & re-installed various updates from Whatsapp & had a couple of responses from Whatsapp devs, but I am still getting the Security Policy Update pop-up.
I removed Whatsapp from my phone last night & I am still getting the pop-ups!
Apparently, you can stop the pop-ups by force stopping the app??
I have done this, so only time will tell!!