I never used Kingoroot, so can't be sure if it provides and option for master mount (su mm) or not. You can switch to Magisk or SuperSU once the device is rooted. If you can't or don't want to, you can use:
su -c 'nsenter -t 1 -m /system/bin/sh'
from commandline instead of simple su. This will make you switch to root mount namespace. For details see this answer.
nsenter is usually available as busybox applet.
Since mount namesapce was implemented in Android 6, this might not be the problem with your KK device.
PS:
If Kingoroot works for you, it indicates that your device has some serious security flaw(s). Do consider an upgrade.
obbfolder – miduja Aug 26 '19 at 13:52mount /dev/block/vold/179:8 /my_sdcardstill givesUsage: mount [-r] [-w] [-o options] [-t type] device directory– miduja Aug 27 '19 at 07:14mount -o rw,remount /; mkdir /my_sdcard; mount -t vfat /dev/block/vold/179:8 /my_sdcardkinda worksls /my_sdcardshows the list of files on the sdcard./my_sdcardis still empty in root explorer – miduja Aug 27 '19 at 08:22mount -o uid=0,gid=0 -t vfat /dev/block/vold/179:8 /my_sdcard,mountstill shows uid=1023,gid=1023 – miduja Aug 27 '19 at 08:45