Hi there,
I haven’t needed to mess with it, therefore I haven’t noticed until now that the Cube Orange (and probably other cubes) use a new and unique INS_ENABLE_MASK when running Ardupilot. I guess that’s why the default value is 127. Good luck with trying any values 1-7 here 
I haven’t been able to find any information whatsoever about this anywhere and was wondering if anyone had any insights. I was able to figure it out with some trial and error, but some documentation somewhere would be really nice.
https://ardupilot.org/copter/docs/parameters.html#ins-enable-mask-imu-enable-mask
I think this had never changed? As the Cubes are always having 3 IMUs.
Indeed, it has 3 INS as always, but what changed at some point for the cube was the position of the enable bits in the mask. I had tried using the very same information you referenced, and it didn’t work. The only value that works from that documentation is “127” (the new default setting 1111111), which covers both the old “standard” position (values 1-7) and others like the cube orange, which is now different (change the 127 to a 7 to presumably enable all three and you will totally break it). Changes like this need to be documented, and also, in my opinion, the reasoning behind such a silly change.