When running in Photon Fusion 2, you may run into an error similar to below:
FieldAccessException: Field `Fusion.NetworkBehaviour:Ptr` is inaccessible from method `METHOD_NAME`
This seemingly seems to be that Fusion is not allowing Networked Objects from accessing their own networked properties.
This error occurs if the "Allow 'unsafe' Code" option is unchecked in PlayerSettings. When enabled, the error will stop occuring.
If you have networked objects in any assemblies, you'll also need to set "Allow 'unsafe' Code" on the Asmdef file too. Tip: Don't forget to include this new assembly when weaving networked objects.
Thank you to @kazuki_kuriyama from Qiita for posting about this previously.