It looks like the V2 player don't apply the Ambient Light setup!
Shot from default player
Shot from V2 player
Ambient Lighting isn't supported on PBR materials. For that reason, it is not included in V2. Hemisphere lighting will help to achieve a similar effect with the right adjustments.
Thank you for the clarification.I was confused, since the option was editable and not disabled. A small note next to the option could help clarify the whole thing. Thanks again !! :-)