The don't like to disclose the cause so as not to show the inner workings of the company. Their are some hard walls up in the industry about what gets discussed and what doesn't because they don't want to crack the floodgates of info and risk a huge leak of damaging or thought provoking topics.
Raw shortage I suspect, one time I tried to trace back where they are getting their yams from to see if that was the case for Test. I eventually received an email full of lawyer speak that I interpreted as a thinly veiled threat something like "fuck off if you know what's good for you".
I probably overdid the suggestions of a yam cartel