5DII metering mode and exposure lock question

Hiya all,

my 5D II, purchased as a 'fill in' between my M8 gear and Phase One gear is slowly elbowing both of them out as I get used to it and see just how good it is. I had a 5D for a long while and had a bag of lenses so it made sense to get the MkII.

BUT (there always is one!) yesterday I hit a glitch: I found that switching to Spot or Partial from Evaluative means that maintaining a half-press on the shutter button no longer retains exposure lock. This seems to be

a) undocumented and
b) counterintuitive and
c) really irritating.

Am I missing something?Any thoughts gratefully received!

Tim

Gallery: http://tashley1.zenfolio.com/