Well, there are a few things wrong in your capx.
1) Don't use Spritefonts for platforms. Yes, you can add the solid behavior, but the best way to deal with repeated blocks of textures are either Sprite objects or Tilemaps. I haven't use Tilemaps yet, so I will suggest to "brake down" your different block types in to separate frames on a single Sprite object (don't forget to set the animation speed to 0), and use that Sprite to lay down your blocks that populate your level.
2) Your thinking was right, but your timing is wrong. You set an event that tells C2: every 1 second repeat those actions, yet, within the same event you have a wait 1 sec action which contradicts it self when the event repeats after 1 second. The Every X seconds condition should be set to 2 seconds. That way the actions within it have the required time to execute. (There are other ways to achieve this, but since this gets the job done, let's leave it be)
3) For some reason, deactivating the "Solid" behavior does not update if the player with the "Platform" behavior is upon the object that has it. Use the "Disable/Enable collisions" actions instead.
4) You don't have to use Families for your example. I used a simple Instance variable to separate the Blocks that we want to vanish recurrently.
5) There is the issue that the Block will solidify it self while the player is occupying the same space with it. I used a "Player is Overlapping with" condition to move the player out of the way when that happens. It's not perfect but it does the job.