Ok looks like I managed to resolve this myself.
I still had a GPO associated that had the Citrix Profile Management enabled (Administrative Templates\Citrix Components\Profile Management). Once I removed that policy my FSLogix profile now works as expected and had an instant performance improvement.
The tutorial I watched on how to setup FSLogix didn't mention about disabling the old Citrix profile management (probably a new setup). I left the components installed just disabled the policy that turned it on.
Hope this helps someone else with setting up FSLogix
This was the guide I followed which was pretty good to be fair https://www.youtube.com/watch?v=ZNbV82Z1PnE