>The ones containing glycerol are sugar-free.

Well glycerol is not sucrose but it has more calories per gram than sucrose and the FDA requires the glycerin content per serving to be declared as sugar alcohol.

>Glycerin (sometimes spelled glycerine), or glycerol, is a sweet, syrupy liquid that is about 75% as sweet as sucrose. It is chemically categorized as a polyol with 4.32 kcal/g. ... If the label has a statement regarding sugars, the FDA requires the glycerin content per serving to be declared as sugar alcohol.

https://diabetesjournals.org/spectrum/article/17/3/137/2007/...