There are several forms of "Glucosamine", and it is made from several different sources for supplements. From a different forum, and different reports I have read, it is very probable some forms of "Glucosamine" are better than others - and thus very probable that it is one form that is the one responsible for the adverse reactions due to "Glucosamine".
AS for "Glycos": Glucosamine is NOT a Glyco, you are right. But its use could be warranted for 'Gylyconutrient Formulas' as it is this that appears to regulate the "Hexosamine Pathway". Glucosamine-6-Phosphate is synthesized from Fructose-6-Phosphate and Glutamine to form the "N-Acetylglucosamine" {GlcNAc}. Bear in mind this pathway is not fully understood, and it may not actually work this way in the body.
AND there are multiple forms of all these chemicals that may actually do different things in the long-run.