I agree your emitters are properly installed now for a series setup but a couple of other things come to mind.
This would be easier if I could mark up your photo but I’m not sure how so here goes, all comments relative to your photo in post 48.
Confirm the jumper pads closest to the + pad are not bridged, hard to tell from the photo.
You mention 7.8ish V from the driver, I assume that’s a dynamic measurement on the + and - wires. Match’s graph “(here)”:More Emitter Test Results (xpg2, xpe2, mtg2) Updated 11-12-12 shows forward voltage of the XP-G2 starting at 2.8V (for only 200mA). I think your available voltage is too low.
I would do a voltage drop across each emitter to confirm. Use a DVOM, first + probe to red wire from driver, - probe to pad at 2:00 in the photo. Second, + probe to 2:00 pad, - probe to P+ marked pad just below center in the photo. Last + probe to P+ pad just below center, - probe to - wire from driver.
If I’m not mistaken, for a 2.8A driver you should be seeing approximately 3.0-3.1V per LED or 9.9V across the driver wires.
But then again I may be out in left field.
Good luck with it.