Pressing the medical kit key while sliding does not work

I usually recover by directly typing “5” (syringe), “6” (first aid kit), “7” (shield cell), and ‘8’ (shield battery) on the keyboard. However, for some reason, when I press “6” while sliding, the keyboard doesn't respond. “5,” “7,” and ‘8’ work fine. I can restore HP by stopping and pressing “6,” but since I sometimes need to heal while sliding, I’d like to fix this issue.