The remaining sugar is your problem. You dissolved it temporarily by applying damp paper, but once the water evaporates the sugar gets sticky again. You should get rid of the sugar residue, but depending on where it ended up that can be a pain. Best chance is to remove the space key and check where it’s still sticky. Be carefull, there’s a delicate mechanism under the key. Watch a video on this if you’re not sure. Tip: use IPA (isopropyl alcohol) to clean, not water. IPA als dissolves the sugar but it does not corrode anything over time. It also evaporates a lot quicker than water. If you don’t succeed in removing all of the sugar you can apply a little bit of silicone spray, that can help the key mechanism to move easier.
Good luck, and remember: a new keyboard is not expensive, so it can’t really hurt much to try the repair yourself!