Of course I solved it right after I posted!! I'll put in fix incase anyone stumbles across the same issue.
Even though my Unity settings were pointing to 2D, the AC settings were not - I just went to the AC settings manager tab and changed the camera perspective to 2D. Doh!
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I'm bringing an old project back to life that has been left derelict for a bit (over a year).
After updating my version of Adventure Creator to 1.64.5, Unity Version 2018.2.8f1 (ae1180820377) Personal, I had navigation issues (before i updated everything it seemed to run fine.)
My character cannot navigate properly - being permanently fixed to the x axis.
I googled how to switch the project to 2D mode, but it already is set to 2D mode (via Edit> Project Settings> Editor > Default Behaviour Mode). Not sure what else to try! Any help will be appreciated. I'll update right away here if I manage to fix it.