This is driving me quite literally insane. 
At seemingly totally random times, in any file I open, when I extrude a face/vertex/edge and try to transform it through scale/rotation/move the entire object will be transformed instead of just the extrusion.
I've actually now tried using Maya 2016, 2017 and 2018 and it occurs in all versions.
The problem occurs entirely randomly, one minute I can extrude a certain face normally and then the problem crops up, or sometimes I can't extrude anything at all without transforming the whole object, sometimes it stops after I reopen a file and sometimes it doesn't. Sometimes it just begins functioning normally again by itself, for 5 minutes.
Example: (After Ctrl-Eing in this case, extruded face highlighted)
Left: Moving an extruded face.
Right: The extrusion arrow that appears when something is extruded works fine, that's how I got that new sticking out bit, when when scaling the extruded top of the new part....
