TC-80N3 and back button focus

I just got a TC-80N3 and have been messing around with it.

I have a 6D and use BBF. When I have the timer hooked up the camera would not auto focus when pressing the timer shutter button halfway in P, Tv, Av, M or Bulb modes. It would only work when set to Auto, CA, SCN, C2 or C1 modes. When I turned off BBF, it worked fine in P, Tv, Av, M or Bulb modes.

Is there a way to keep it set to BBF and still use the TC-80N3? Or do I have to change that function each time I want to use the TC-80N3?

Nevermind. I finally found the answer in a search.

And what is the answer?

From what I read, you cannot use BBF with the timer. You have to switch AF to the shutter button.

Yes, that's my experience - remote shutter only activates the shutter button.

If you AF on the tripod a lot, it may be worthwhile setting up one of your custom modes specifically for tripod work, with AF on the shutter button.