Samsung Galaxy S6 Edge — S7 edge update to Nougat affecting WhatsApp?

Hi..i have a Samsung s7 edge on which I recently updated the Android version to Nougat.
I sometimes tend to read messages received on WhatsApp after turning data off (or by using flight mode) so that my "last seen" status doesn't change.
However, over the last few days I've noticed that doing this doesn't freeze my "last seen" time as it used to! Clearly this has caused a great deal of consternation amongst some WhatsApp friends who have moaned that "oh you've come online but haven't bothered to read my message!"

Does anyone else have this problem with WhatsApp? I'm not sure if it's linked to the Nougat upgrade and I can't think of anything else other than the possibility that I need to wait a few minutes after turning off data before I go into WhatsApp. Do I?

Thanks for any helpful replies.

EDIT: Is it possible to downgrade to MM without rooting my device?

— modified on Mar 30, 2017, 1:01:13 PM