Default [Q] Unable To Mount System Safestrap

so i decided to install safestrap to try out a rom. the install went fine and the recovery install went fine. i hit reboot recovery in the app to get to twrp. the first thing i did was try to make a backup of my stock rom. during the backup process twrp says it was unable to mount system so backing up /system failed. i tried to go into mount option and enable system mount but the check mark doesnt go into the box. it just hangs there highlighting the box. anyone know of a fix for this?
Link to my Dev Host Files =