Sorry, it's crunch time and it seems this software is rebelling against me! Anyway, see thread title. It must be the pressure because apparently I am missing something ridiculously simple. But I cannot record a scale keyframe for a simple plane, even in Object Tool mode! I've deleted the track and tried to start from scratch but cannot record the keyframe; any scale change I make overrides all other frames.
EDIT: Ah, the wonderfully helpful solo mode in the timeline was turned on for one of the tracks. Lovely. Lesson here folks. Never use solo. Ever.