For me this occurred for the first time after 10.1 dropped. I tried your fix and it worked.
HOWEVER, every time I logged in it reverted back to locked with the shift key as the modifer for moving icons.
I located the culprit of it being swapped back every time. It was ELVUI
Under Actionbars if you have Lock Actionbars selected, there is a drop down that appears above that is preselected to SHIFT, so this needs changed too in order to fix the SHIFT modifier for macros