This appears to depend on where you place the base point. I tried placing the base point both at world 0 and snapped to one of the boxes and then it works fine. When you just pick a point in space, as you do in that clip, then it doesn’t work. Your geometry is far from the origin and the distance to the base point probably gets very large. @stevebaer, is this a display issue that you could look into?
Note that if you pick a shaded display mode, you will be able to see the mesh as well - but it still doesn’t show selected when you select the block.