I couldn't figure out why I couldn't jump/stand to access something critical anymore (an objective item), turns out it was because I'd added absence_noticeability to an object that had to be moved out of the way. Apparently the invisible-to-player marker that is put there for AIs to notice when something is moved out of position was impeding jumping, and forcing a crouch if moving a higher object to stand upon. Just something to keep in mind for the future!