Linux Mint 19
Intel 630 Graphics
Blender Beta 5 June 2019
Open default Blender.
Select 'millimetres' as the unit.
Shift-A and add a new cube.
Change the 2000mm to 6mm (I was following this: http://www.rab3d.com/tut_blen_2-80_608-1.php)
Zoom into the cube and while the zooming continues to work, the cube disappears when it takes up about half of the viewport.