I select a clip, zoom right in and select a zero-crossing to split it at.
 
I then right-click, select Split... and in the dialog I select Time Format "Samples".
 
I click OK.
 
RESULT: The clip is split at the nearest time stamp, NOT the selected sample!
 
I undo (ctrl-Z) and try again, and now it works correctly.
 
Seems like the combo box does not change the variable that is used to determine the time format. Instead, the split tool uses the previously saved value.
 

At least you can get it to split! I can click all I want with the scissor tool but the clip won't split anywhere!