Hi!
We discussed about this some time ago on the WIA beta forum so i think i can give some more info
Is a little more complicated than: unnactive=locked
With the hardened activation option enabled a stack commanded by an inactive leader will become locked in place (the whole stack) for the turn on a % chance depending mainly of the military control of the region.
In a region 100% under your control the stack will lock 50% of the time,s and then up to 100% locked with 50% or less MC.
I think the idea is that inactive leader can function more or less normally on their own "backyard", but have problems to advance on enemy/contested regions when inactive.
In addition there are some bonus for not getting locked if you are low on supply or completely unsupplied.
On AACW i think the numbers are the standard, so, posting a neat table Lodilefty did

, chances are like this
[ATTACH]7456[/ATTACH]
On a recent patch on WIA (not sure if its on the 1.04c or on a future 1.05 beta) they were tweaked and the no supply bonus increased so a nearly starving stack won't get never locked in place and can run in search of food.
You can check (and tweak) all this on one of the files on the settings folders: command&leaders.opt.
Oh, i forgot!
In addition...
"If a leader has the Ability Over_Cautious an additional roll is done:
MC >= D100
If this test fails the commander will be not active." Primasprit dixit
Regards!