I haven't used 6006 lately, but I used LX's in it when I did. But here is my theory, batches of wax and oils for that matter are very inconsistent, so depending on the batch, the weather, the pouring conditions, etc. I think that it will never be 100% perfect all the time. You can drive yourself crazy with wax/wick combos. I would just test away til I found the best combination and go with that. There will be fragrances that you have used for years and one day, BAM, its not working like before.
Good Luck though, the struggle is real.