Add the an instance variable (boolean) to the platform named "trigger"
Add the Fade behavior on your platform and name it FadeOut.
--With these properties:
---Active on start: Yes
---Fade in Time : 0
---Wait Time: 0
---Fade out Time : 1
---Destroy after Fade out : Yes
Add these events:
Comment: For the trigger
+Player - On collision with Platform:
->Platform - set boolean (trigger) to true.
Comment: Fade Out (Destroy Fade Effect)
+Platform is boolean (trigger)
++Player is not overlapping Platform
-->Platform - FadeOut : Fade Out start
Comment: Anti-Solid Bug
+Platform on destroyed
++Player is overlapping Platform
-->Player - Set Y to (Self.Y + 1)
I hope that works out for your game.