If the Clouds are covering the Blocks, try clearing the Clouds with the Cloud Cleaner.

To activate the Cloud Cleaner, you need to match the same color Blocks as the Cloud Cleaner, and you need to match them according to the number written on the Cloud Cleaner.

You need to clear the Clouds with the Cloud Cleaner in order to see the Blocks and Obstacles that's hidden under the Clouds so remember to activate the Cloud Cleaner as soon as possible!