Exiting sketch only leaves shadow

Hi,

I have been using  SW's for a fair few years. In downloading the new 20/21 it now doesn't work when I exit the sketch and leaves only a shadow.

As you move the curser over the shadow orange lines appear and disappear to show where the 3D object should be.

My PC has the right spec and I have attached the screen shot.

Does anyone have any ideas as to what might be the problem?

Many Thanks

Sally

SolidworksDrawings And Detailing