Hi after importing the model, 3D window is blank. File is imported and 3d Objects window also shows the objects but nothing in the 3D window.
First ensure that all your models are loaded -
If yes and click on right-click > zoom all still doesn't show the model, it's likely that there are floating elements very far from the base model location and everything is extremely zoomed out and not visible. To confirm this, you can select just one object from the tree and zoom into it.
Please refer to this thread on identifying far away objects - Is there any way to get the coordinates of 3d object?