I extract each new version of the game into a unique, brand new folder, and I've gotton similar behavior from the game. Though in my case instead of kobold caravans it was goblin caravans. Interestingly enough both goblins and elves arrived at the same time, both with caravans, and both setup shop on my trade depot. I was able to use the trade depot normally and even had the option of selecting which caravan I wanted to trade with, which I thought was rather neat.
The downside is that conflict seems nigh impossible in the current version, with dorfs being at peace with everyone. My game is somewhat heavily modded, but mostly having to do with minerals, metal, and reactions. The only changes I've made to the civilizations file is to remove the babysnatcher tag and to remove clothes from goblins so my dorfs don't spend years cleaning up after a siege. I've also copy and pasted the human ethics into dorf ethics after noticing humans tend to be at war with everyone, but goblins and dorfs still refuse to fight. I've actually been at war with the elves more often than the goblins, but that was only one time in probably two dozen worlds. The only way I've been able to induce the goblins into sieging is to remove the [INTELLIGENT] tag from goblins. This causes all sorts of wars as they're unable to communicate and does cause them to siege, but it seems to break the siege behavior. They just stand around at the edge of the map doing nothing.
EDIT:
I'll try to get a save of this behavior. I didn't think to do it the first time it happened.