Possible to get Sugar Syrup and Coconut Oil to solidify together (Emulsifier needed?)
Coconut oil isn't ever a 1-1 swap with dairy butter, which has a small amount of water in as well as compounds that allow it to emulsify.
If you're avoiding butter, try using a good quality margarine instead of coconut oil.
Lecithin granules work well. Add half a teaspoon at a time, whisking it or using a hand-blender. Agar and xanthan gum are both good emulsifiers but might cause it to thicken up a bit too much as a lot goes a long way.