As others have noted sometimes you have to wait for three clicks before releasing the door lock/unlock button from the "unlock" position and immediately removing the key. Quite by accident I missed the second "click" (which I'd tried several times without success) and held for another "click", then removed the key. Now all doors unlock when putting it into park.
'09 Fit Sport Auto w/Navi.
My undying grattitude to both qbmurderer13 for pointing me to this thread and CrystalFiveMT for posting the procedure.
Kompai!
