If the robot is transporting a blue block, it is not able to detect a wooden block, because it is trying to go near it in order to use the light sensor, but the claw touches the block.
Check if we still see an object:
If Yes: begin obstacle avoidance
If no: just let it continue what it is doing (it will go near it and detect a blue block).
If the robot is transporting a blue block, it is not able to detect a wooden block, because it is trying to go near it in order to use the light sensor, but the claw touches the block.