Thank you! But I've already done that and it doesn't solve it. Only solution given by Blackview customer service is to keep all apps of interest open in background, which I consider a very poor solution. That's why I'm looking for some way of overriding this configuration.
My Blackview won't allow closed apps (whatsapp, banking app...) to send me notifications. The Blackview options don't let me change this. However, other apps like email apps can notify me even when closed. Is there a way to override this? Cheers