The PHB States that surprised characters cannot move, take actions or reactions until the turn ends. I had several fights where surprised enemies moved and shoved me. Some monsters are immune to surprise but i looked up the spectator in the MM and could not find anything. So its either bugged or wrong.
I too have had this so many times, I really hope they sort it out and not roll the game out and then do a better version later like they did with DOS2. Lets not mention Detor....err NO! The shear rate of enemies rolling a save on the Thunderwave spell is frankly astounding, I'm literally having to save scum at least 15-20 times in some cases for it to actually work on my present run and that's a high roll against a sorcerer with 18 Charisma so the die are still massively loaded in the enemies favour.