If it doesn’t smell or taste yogurt-y, try using a different probiotic. I have great success with Garden of Life Raw and I’ve heard that PB8 does well. You could also try a different coconut milk. I generally use Native Forest. Look for something without carrageenan. Guar gum is ok. You can also try leaving your jar in a warmer place (maybe even trying the oven light technique.)
If your yogurt-in-the-making separates in the jar, that’s ok. This will happen, especially if there is no guar gum in your coconut milk. What I’ve done is let it percolate until the top, thicker part of the yogurt tastes to my liking. Then I pour or scoop it out, discarding the watery part.
Remember, home fermentation is not an exact science. But luckily it’s a fairly inexpensive experimental art!