I am using Simple Skins & Capes: Reloaded, and SpoutTitle (I know it's out of date, but trust me, it works.), and whenever I vanish/unvanish, it disables PlayerSkins (the name of the .jar for Simple Skins) and SpoutTitle. The plugins are still technically active, just no longer work. When I try to change my skin with /playerskin, it says "Player [MyIGN]'s skin has been set and saved", but it does not change. Likewise, SpoutTitle, which hides nameplates above players' heads, and is useful for the role-play server I'm currently developing, stops working. Players that have vanished and unvanished's nameplates are once again visible, and they weren't before. (I like to use SilentJoin with FakeAnnounce, but with this bug it renders both mentioned plugins useless for admins right from when they log in)

Both are Spout plugins, right?

Well, regardless of what they work with, either they or spout need a fix. It's not a VNP issue.