I completed Halo 4 missions 1, 3, 6, and 7 solo on Legendary.
After a week of not playing, much of my local Halo 4 memory was erased, the Infinity mode introduction played again: Armor and loadouts were reset, campaign progress was gone.
However, the last mission I had been playing (mission 8 solo on Easy) was still saved via "Resume Campaign". I finished that level, but all the levels before it are still locked. My campaign progress is still on the Halo 4 Stats website.
So, if I play through on Easy, switching to Legendary only for the missions I had not previously completed on that difficulty, so that it would show on Halo 4 Stats, that I completed every mission on Legendary, will I still unlock the "Lone Wolf Legend" achievement?
Or does it only unlock based on local memory of campaign completion?