Long read...buckle in.
Hopefully you isolate the root cause. It shouldn't be that hard to source.
You said it was on the winter tire that was taken off last year and not noticed until now. What kind of shape are your warm weather tires in? I'm assuming they are ok or there would have been some mention of it - unless I missed that bit. I'm thinking the car was driven with the parking brake engaged and that tire was your sacrificial lamb.
If you have had a seized caliper, I think you would have noticed it. You would have smelled burning brake pads, well at least until they wore out completely, then an awful bit of squealing. The a front caliper seize would really throw off your steering and braking and a rear would make the car feel like you are dragging something.
There are a few more scenarios here but like
@ToSlow said, this isn't rocket science so finding the issue should be pretty straight forward.
As for the AWD, I hate to be the bearer here but it is very important that the tire circumference are reasonably equal among all 4 tires. Mixing new with warn tires will stress the transfer case potentially causing a much larger issue. Some will scoff at this advice. If you are uncertain, YouTube is your friend and you will find I was trying to be a kind soul.
For what it's worth, if you are staring down the barrel of a full new set I would like to turn you on to the Michelin Cross Climate all weather tire. I have had these for the past year. Handling and performance are incredibly good. In the winter (last winter was a good test), it has been the best performing winter tire I have had. I have used all the top brand winter tires including the Blizzak, X-Ice, Yokohama IceGuard and Firestone Winterforce. The Blizzak were great for one season and absolute rubbish for the rest of the life. I would never buy the Firestone again either. The X-Ice and IceGuard were really good. The Cross Climate is taking the cake for me. Rotate every 10k and carry on.
I am a research hound and really believe that tires are the second most important safety feature on a vehicle. You being the first. I do my best to buy the best tires I can afford. Of the 5 vehicles in the house, now 3 are on the Cross Climate. The other 2 will be when they need tires.