I have an application that vibrates at certain times. It works perfectly on the A40, but when it goes into sleep mode it no longer vibrates. I have not found how to activate it. On a mobile from another brand it always works. Any ideas?
Sleep mode turns the app off which is why you are no longer able to receive any kind of notification (vibration in that case). You can enable this from Settings> Device care> Battery> Menu (3 dots top right)> Sleeping apps> Turn the slider for this particular app off.