sd card is empty when using su I have strange issue.

I've just installed Supersu.

With regular user (not su ) the sdcard shows all contents as usual,

But on doing  su , I see (with "ls") that /sdcard is empty (though it is not) !, on going back to regular user, I see files again....

Any idea what's wrong ?

Thanks,
It is likely due to mount namespace separation being unchecked in SuperSU app settings

For an explanation of what it does and how it could possibly affect storage not being read see Mathew's answer here, also the link referred to therein

Aside, sometimes TiBu also asks you to do the same if SD is not recognised