Stickiness on leather or vinyl is a chemical reaction between any of the following: worn factory finish, body oil, residue from a cleaner or conditioner, or a combination of these factors.
Stickiness must be treated before a new finish is applied. Odorless mineral spirits or denatured alcohol are a good first try. Acetone should be used as a last resort and with caution. Body oil stains that remain sticky likely will require an oil extraction and/or the application of a blocker by a professional in your area.