Yes this is quite obnoxious. I noticed the globally selected reportsuite only refreshes the reportlets if you were already in the dashboard...
say you have a dashboard that you created while being in reportsuite A...but want to open the dashboard while you were already in report suite B, if you do this it will show data for A, even though you are in B.
To have reportlets refrsh to the suite you want to, you have to do one of two things:
1) First open the dashbaord, then select a global suite.
2) if you are in a global suite, and then you open dasbaord, you will get data for the suite you created the dashboard in, so you have to select a new global suite and then go back to the suite you are intereted in.
Not very good UX. Leads me to belive its a bug, but when I asked client care I was told its working as designed.