to recreate:
add directory to playlist -> a or A
start track -> enter (on playlist item)
clear playlist -> C
(playlist section becomes empty but current song still plays) (this is ok)
add another directory to now "empty" playlist -> a or A
at this point the next song isn't selected only from current playlist but from a playlist composed from the current displayed one and the old cleared one instead, (bug i suppose)
how the next song is started doesn't matter:
end of the current song playng,
starting new song with enter on playlist tab,
changing to next song with n
have the same result, the actual playlist is composed now of old (not shown in playlist tab) and new items (visible)