A: Try subsetting the drillhole data (ie. turning off a number of drillholes/sample points in the Attribute Manager) to less than 40,000 visible points and then see if the icon becomes active.  If so, open the 3D spatial window and then turn on the visibility for the other data points. There is a data limit set for the number of points that is preventing all of the data being able to be opened into the 3D plot window initially so the workaround is to only open a small number of data points first of all.