I imported my model from Solidworks with urdfconverter. The robot looks fine in Rviz,but in gazebo, it looks submerged and the prismatic joint doesn't work well making the table fall. Also, the fixed joint doesn't appear. During starting, the robot moves.

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For these problems, I searched and one said that "try to correct the inertias". I tried to correct them, but with nothing happened. For the fixed joint I found that it is better to put it revolute with limits 0, but this makes the transformation in Rviz collapse. I am using ROS melodic and gazebo 9 Thanks, This how the robot appears:

The table falls after running the simulation

This is the urdf file: https://drive.google.com/file/d/1C80a...