I am using M31, model number SM-M315F/DS with Andoird 10 update released by Samsung on 7-Mar-2020.
WhatsApp on this device goes completely inactive some time after the screen is turned off. If I unlock the phone and run WhatsApp again only then I receive my latest messages (so don't confuse this with notifications issue). Phone screen off -> WhatsApp off!
I have allowed the app to use data in foreground, background and also in data saver mode. I am not sure what I am missing.
Any fix for this would be extremely helpful.
Thanks in advance,
Sorry to hear that you're having issues.
Do any of your other apps stop receiving notifications when your screen is switched off?