I see a few things I'd suspect if it were me.
First, one mix has honey, which I've heard can have gluten. Then there's the yeast. Also, corn products and corn starch aren't necessarily equally safe. Some corn is organic, others are GMO, which I know I react to. I'm not entirely convinced that it need be a common ingredient, but I agree it's a good place to start. The cane juice I don't know much about, as I don't do sugar.
As for guar gum being a laxative, that's what Wikipedia says, but recently I read the opposite

From my experience I'd have to disagree with Wikipedia this time, sadly. It's the insoluble type which is used in laxative products isn't it?
Here's what Wikipedia says about dietary fiber:
http://en.wikipedia.org/wiki/Insoluble_fiberQUOTE
Sources of dietary fiber are usually divided according to whether they are water-soluble or not. Both types of fiber are present in all plant foods, with varying degrees of each according to a plant’s characteristics. Insoluble fiber possesses passive water-attracting properties that help to increase bulk, soften stool and shorten transit time through the intestinal tract.