Why can't I select multiple objects? I am currently unable to select more than one object at a time for some reason. I have object mode selected. I then use shift + LMB (mouse buttons swapped from Blender 2.78 default). But the select just moves to which ever object I select and deselects any object I had already selected. I also tried box select, which now selects nothing. I have applied transformations as I know unapplied transformations can make things screwey. It was working just fine earlier. Any help would be much appreciated.
OK the problem was the theme. With ScienceLab theme the colour of selected and unselected objects is too similar for my eyes. Had to modify the theme.