I just received a Samsung Galaxy A3 2017 with a neon flip cover.
The issue I present is the ringtone stopping after 2 seconds when receiving Whatsapp calls with the flip cover closed, toghether with the vibration and the fancy edge lights, full mute while the call is still calling.
No issues if the cover is open.
No isssues with normal telephone calls.
Updating Whatsapp, reinstalling it and resetting the phone doesn't help. Changing the ringtone to a longer one too, the phone just cut the ringtone.
Tried also excluding Whatsapp from the battery saving, same bug.
A similar topic has been already opened in this site with no solution.