This issue appears to be the same as 1233 raised against the Nintendo switch but I thought I should raise a new issue because my problem is on ps4. 

When starting mincraft dungeons at the screen with the option for player 2, P2, to join by pressing L3, press down on the left joystick, there is no response to the input. The problem is persistent on a players account. On another account L3 is responded to but the joining players dungeons profile information is unavailable and they have the option to create a new profile or clone the existing P1.

It is very frustrating that this problem has only appeared in the latest ps4 update from 3 or four days ago. It has worked perfectly up to now and is the way we usually play.