No worries, thought I saw something when loading up my save form the title screen but clearly was losing it ;)
There are too many great details and enemy animations in 3d for me to play completely in 2d mode.
Having played 3D I will say this about 2D... you are definitely losing a lot of the game. A lot of character work, interactions, cut scenes, world building just isn't there. The 2D game is really great and done really well (I would love to have seen the monsters animated in battle) and it plays much faster as it effectively shrinks the world down so for me its ideal to get back to my previous furthest progress point on the PS4 but its definitely obvious that it wasn't a game crafted solely to be 2D.
The ideal way would be playing through both versions or switching every other chapter I guess.