Can't sprint and crouch/slide at same time?

[Zagnew18]

Hi all, for several months I've used a gaming keypad to play Warframe. I left the Warframe controls on "default" and used the keypad software for my binds. I was always able to be sprinting and simultaneously use "hold to crouch" without releasing my sprint key. Now, I'm finally doing away with the keypad and re-adjusting to the main keyboard itself. I am an ESDF mover, I have my sprint keyed at "Z", and hold to crouch mapped for "C" as this is comfortable for my hand. For some reason, however, I cannot use both functions simultaneously. If I want to use the crouch/slide function, I have to release the sprint button first. I do not have "toggle crouch" mapped at all as I never used this function, I only use "hold to crouch" so that I am standing again when I release the button. Any thoughts on why I wouldn't be able to sprint into sliding without releasing the sprint button first?

Edit - *Update* - Upon further tinkering, I found if I mapped the sprint/roll to "Ctrl", then this function worked just fine, I could sprint into a slide without having to release the sprint/roll button "Ctrl". But with sprint/roll mapped to "Z", I would first have to release "Z" before pressing my "hold to crouch" button to slide. Is this simply a bug?

Edited November 9, 2018 by Zagnew18
*Update*