Is Halo 4 Achievement Lone Wolf Legend based on local console memory only?

Question

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?

Answer 1

Just to confirm the current state of things:

Last mission, on ledgenary - half way through

Rest of the missions prior to this: Locked.

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Yes, if the game works as Halo 3 / Reach did, each mission has a marker "highest difficulty completed" - the same marker you can see online. The order you complete the missions on won't make a difference, as long as you get the local marker saying each mission was completed on legendary.

However, I'd be making sure you know why the memory was wiped before carrying on - It'd be horrific to play through again only to loose all your progress. All the markers for each mission need to be on the local system - it doesn't matter what it shows online.