I know it's a long shot, but would you happen to be able to post some pics of the jug the last fill came out of?
I've never seen DEF exhibit the characteristics you listed. I've seen it freeze then thaw and be completely useable. I've seen it get "warm" and evaporate, leaving a white crystalline coating behind. But I've not seen it turn any color or smell of anything other than urea.
I feel silly saying it, but the problem isn't always readily apparent. WalMart used to sell it's Super Tech brand DEF and motor oil in identical containers. Is it possible you picked up a jug of something other than DEF in a container that looked similar to the DEF container?