Rviz shows gray point_cloud

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Hello,

I have a very strange problem. I have ros melodic on my computer and also in another one. When I play the same rosbag file which include a PointCloude2 topic on the first computer I see just gray points and in the second computer I see with colors. Also, I'm not able to change parameters in Rviz for the topic (like: size, alpha etc.) while in the second one I can.

I tried to reinstall Rviz but it did not help. This is happen also if I am working with the lidar itself in live and not with the recording.

Furthermore, if I work with ROS2 on the first computer with ros1_bridge and open Rviz2 I can see it with the colors and everything is fine.

What can cause to this situation?

Thanks Aviad