but did you bugitem?

There is no bug with the dispel runestaves. All offensive runestaff flares (which are all flares except mana) do not trigger on spells that are auto success (such as Spirit Dispel (119), Sounds (607), etc) or mass attack spells (Nature's Fury (635)). The dispel flares will trigger with other spells such as Sunburst (609), Spike Thorn (616), etc. For additional specifics, you can reference:

https://gswiki.play.net/Runestaff_(saved_posts)

GameMaster Estild