A search turned up similar issues, but older, and with no resolutions or resolutions which did not work in my case. Here is my tale.
I have three squads, two of them stuffed full of axedwarves I am quite proud of and one set of two marksdwarves for flavor. They all train for glory and skill in their wonderfully appointed and massive barracks complex near the entrance to the glorious city of Ikuddastot. Adjacent to their main room are storage departments where all of the city's arms and armor are stored. Specifically here, we are looking at the armor storage.
All was going quite well for the longest time. For a couple of years by my reckoning the armor storage had blossomed into one smaller, closer pile and a supporting rear pile to hold more shtuff. The smaller pile fed from the larger. Fine. ..Until recently. Don't ask me exactly when, and certainly not why, but several of my otherwise honorable and sane wardwarves decided to take it into their minds that they much preferred running back and forth across the armory to constantly 'pickup equipment'.
From what I can tell, they fiddle with some mail\breastplate or combination thereof and then walk away a few steps. They either then return immediately to do the same again or, because they've dropped the equipment onto the pile rather than into a bin, come back after a helpful' peasant has come along to tidy up and stuffed the equipment back into a bin. I surmise that this causes existential dread in the wardwarf who, attached mind body and soul to all armor he has ever witness and no longer able to see it, fears he may vanish from the world.
Frustrating\amusing theories aside, I developed a headache. It was late and I wanted sleep without nightmares of running dwarves, so I tried various things to stem the flow of madness from the dwarves into my mind:
-Assign other orders, both through schedule and\or through the squad menu (orders unheeded, too busy fondling equipment);
-Forbid the entire disastrous pile (dwarves frozen in place, with either 'pickup equipment' or 'no job' until the equipment was reclaimed);
-Remove the stockpiles entirely (same effect as forbidding; without a stockpile, dwarves can't see the armor at all?);
-Remove the use of bins from the pile (same effect as forbidding; for some reason dwarves in this fortress will never under any circumstances store anything in any stockpile without a bin if it can be stored in a bin. Don't know if this is related somehow, other than I think that the dwarf who is performing the 'pickup equipment' is I don't think so much putting the equipment onto the pile under him as simply dropping it where he stands when he's done.)
-Alter the uniforms (no change);
-This morning, utterly disband all squads, wait a while, create new ones manually (to my horror, no change);
Now, this city I am extremely proud of. I deliberately embarked into a frightfully haunted forest, found that the trees do NOT regenerate, lost many a brave dwarf to skeletal beings and a Collosus, have survived ambuses and near-famine.. Despite all this, the dwarves flourish, and I have grown attached to their simple little lives. But at this point I begin to contemplate.. surrender. :\
I try one last hope. I remove the secondary pile and replace it with a seperate pile each for each segment of armor, leaving the original mix-all pile. The dwarves do a lot of fiddling around while I bite my nails, but.. it settles. .. NO! NO DON'T GO BACK TO THE PILE! NOOOOOO! The issue seemed to be isolated to the pile with the body armor, so I forbid that pile in a fit of pique, making sure none of the dwarves were seeking their dread equipment at the time.
...It worked. BY ABOD THEY ARE TRAINING! I'm afraid to do anything else. I've looked through the other bins in the other piles and can see that, despite my orders, they're mixed. There's body armor in the shield bins and greaves in the helm bins. My next experiment will be to dump all the armor out of those bins and see what happens. Then I will unforbid the body armor pile and do the same, and see what happens then. If it breaks again, I will attempt creating a uniform which does not incorporate body protection. All the while I shall pray that an ambush does not strike, as I have been lucky this far...