The 0.12 pre-release configuration of Jaeger is configured to use the OAuth proxy, but its done in an insecure manner and it does not work with Kiali.
The OAuth proxy is configured to allow any authorized user to access it. This means any user can log into Jaeger regardless of what permission levels they have.
The OAuth proxy is also only configured to work through a browser and doesn't allow service access. This means that Kiali cannot properly communicate with the Jaeger endpoint and it considers Jaeger to be disabled.