I would imagine because it's not a big seller. Panera discontinued the Sierra Turkey, it's not on the menu, but you can still order... might be able to that with the sandwich you're missing.
Maybe because it was limited time only
Not sure.. probably popularity and keeping it fresh was difficult
It could be also that it is fall now. Usually they sell salads in the summer then discontinue but just for the season. I had an awesome chicken salad sandwich at Panera Bread though.
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