Cinemachine Collider 2018.3 Stops working

So i have upgraded a project today from 2018.15 to 2018.3 where i have a free look camera and a cinemachine collider added to it from the extensions. However it does not work anymore, strange behaviour though as it works for roughly 2-4 seconds then stops detecting the collisions and never adjusts the camera again.

I have tried adding a new camera to the projects, checked all the collision layers are correct and also my project settings for the physics.

Is this a bug with 2018.3? or something else.

 

Actually to add to this i have now noticed that even my Physics.RaycastAll doesnt seem to return the correct array ie not all the results are there.

 

This is 100% the same bug we're experiencing when upgrading from 2018.2 to 2018.3.
Though it's not really related to cinemachine and it seems to only happen if you upgrade a project. It's raycasts overall that will suddenly stop working like they should, and it seems to be easily triggered by the camera colliding with something, so I guess it is related to the raycasts/collision checks that are being done by the camera collider, but it can be triggered by other things aswell. Here is someone else having the same issue when upgrading a project: https://forum.unity.com/threads/raycast-bug-video-attached.595516/