unable to add user to visible list

the subject is pretty clear

when i try to add someone to visible list, it appears as if they were
added there, but they are not- they don't see me. to clarify this,
when i log off/on, they are not invisible list

i can add users to groups, that is saved, or remove them from visible
list, that gets saved too.
but when i try to ADD them to visible list, it simply ignores it. it
shows as i did but after i log off and on i see it did not add them in
the list