I'm not sure this is the same thing that you're complaining about, but there seems to be a bug that when "Snap" is ON, and you hold down SHIFT to toggle Snap (off), you indeed see how the cursor/position line moves freely, no snapping, but when actually beginning the range selection, the range is snapping even though SHIFT is being held and the cursor/position line moves freely as if Snap was off.
The bug continues:
If you hold down SHIFT before beginning your selection, the toggling off snap will not work both for the start and end of the selection. But if you start the selection and then hold down shift, the toggling snap off works and the selection will end freely.
These bugs are most probably due to the shift being used to toggle snap, and to "add to range selection", at the same time. "Adding to range selection" should be switched to CTRL or ALT, instead of and bugging up the "toggle-snap" function of SHIFT.