Gaming

I stored stuff there for ages on my first play through 

Did you check back regularly? Sometimes some containers respawn and others don't. I think the "more informative console" tells you if it's safe storage but it doesn't always seem to be accurate so I don't trust it. If I place a container in the world, I know the stuff stays. (Though if I were to place it in someone else's home, I'd have to make sure it belongs to me and not them, so I don't have to steal the stuff to get it back )

I checked back frequently because I was storing all my stuff there, and I'm a lootaholic that picked up everything I could find

Not barrels and chests.
Cupboards and dressers.

If you check back frequently it won't have time to respawn. If you accidentally stay away for a bit... (10 in game days? Or maybe it varies...) they might respawn.

I've left stuff in a barrel for several weeks, possibly even months and the stuff was still there when I went back 

EDIT - The only time I can recall ever seeing any loot respawn is when I have returned to location due to a quest. Everything else usually remains looted no matter how long ago I went there.

Maybe because you don't return to already looted locations unless you're there because of a quest?

But yeah it's inconsistent, but that's precisely why I don't trust the original barrels and such, unless they're in your home.

I've had lots of places respawn. A good example is Valtheim Towers where I died the other day. I don't recall having a quest there (maybe one of the random fetch quests but certainly not a major one) and the entire place has respawned and repopulated at least six times during my looong playthrough.

I think some of the inconsistency comes about from the difference between safe containers and safe locations. Safe containers are safe wherever they appear in the game and in safe locations every container is safe even if they don't normally appear on the usual safe storage list.

And now back in ESO I have no safe storage at all apart from that full chest and my nearly full bank.
I yearn for the days of Morrowind when you could just leave stuff anywhere.

You know how I always claim that M'aiq shows up when someone's about to attack you? Well, today he showed up together with that invisible dark brotherhood assassin.... and apparently I accidentally attacked M'aiq too, so now he's a red dot and screams and runs every time he sees me.

At least he's not attacking me, himself.