Doug, same tender issue for turning the lights on when connected to the tender. On off is in my future as well!
I had the same issue, and it is usually related to poor connection to the battery. I thought mine was solid, but it has to be a very clean connection. Since my results were not consistent they sent me another controller box with a blue cable for an ACC input, which would act as the on/off switch.
This essentially eliminates the current or voltage sensing option and hard wires it to an ACC input. Now it is 100% reliable.
Call Phillips support... they should take care of you.