That’s why I wrote this. 
I’ve seen it elsewhere on the forum from other users too - not specific to only the xbox controller. It seems that there are some bindings that won’t work with a multiple combination. If I recall correctly, it’s more on some joysticks - but that could be that most use that rather than the xbox controller.
I’m sure it’s not a bug, but rather it hasn’t been coded. But I can’t say for 100% certainty.
You could submit a zendesk on it as a bug. If they respond as “Solved” - that means it is a bug and they know about it. Any other response from them, resubmit it as a “Feedback & Feature Request”.