I have a problem when you tp to a player it will show you as visible when vanished and if you are stand with a player and the player logs out then they log in you will be visible to them when you are still vanished. This is only a problem that I know that is in Bukkit Build: 2060 along with this mobs can still see you and try and kill you.

Also there was not error in the console.

-CLGREEN

Known bug in 1.2.3 bukkit. Waiting on them to fix.

Resolved