APM 2.0.27-rc1 Ch7 & Ch8 Opts Gray

Apologize if this has been answered elsewhere, but I did all sorts of G**gle searches and come up dry.

I’m running APM version above on Linux machine connecting to a Pixhawk 2.4.8. When I do radio calibration, the system can “see” all 8 channels of the X8R receiver. But when I go to extended parameters, the channel 7 and channel 8 options are grayed out.

There’s got to be something simple. Already had APM check for updates, and it didn’t register anything.