CQ5.5 Issue with Run Modes?

Is there a known issue with setting custom run modes in CQ5.5?

I've been trying to set a custom run mode on my local publish instance of "publish,local". I've been trying to do so by adding the sling.run.modes property to the sling.properties file under crx-quickstart/conf. CQ does not seem to pick that up. It appears the only way I can get my custom run mode to register is by changing the RUN_MODE variable in the startup script.

I'm verifying that my "run mode is registered" by checking my run modes in the Sling settings tab of "Configuration Status" in the Felix console. Could it be that this is not entirely accurate and that I actually AM registering these run modes?

Making the change to the "start" script is an acceptable solution, however the documentation insists that the sling.properties approach should work. I was wondering if anyone else has had problems or knows of an outstanding issue with this in 5.5.

Thanks!