Whenever you have a potion effect on you and warp to another world (For example the end to the overworld) the effect will run off. Hope this will get fixed if not intended

That's probably a glitch with the game itself, not bukkit/plugin settings that could be fixed by staff.

Ah nevermind figured out how to fix it. If you relog the effects come back

Wish I knew that before I wasted all my strength and fire resist potions D: