You're using the wrong type of wick and also the wrong size. Tunneling occurs when the wick is either too big or too small. In your instance with the picture shown you are using a wick that is too small, so it will only burn to a small diameter, but the melt pool is too deep in the small diameter due to the size of the candle, so the melted wax is drowning the wick, which is causing it to go out.
You don't say what size wick you are using, just that it's a standard cotton wick.
My advice before making dozens and dozens of candles, only make a few and make sure they burn absolutely perfect for your application before making more. I would also recommend starting with 1 type of wax, 1 type of jar, no coloring, no scent. Get it to burn right and take copious notes on EVERYTHING you do up until the point of getting that perfect burn. Once you do, then introduce 1 thing at a time (either a colorant OR a scent) and take notes on that testing so you have a base as to what your candle should burn like, because every time you introduce something new, your candle will burn differently.
This is how candlemakers test their candles.
Candle Science is a good starting point and a good guide, but I always find that they recommend wicks that are a size or two too big, and you end up having to test for your application anyway. Just keep that in mind when ordering from them.
Good Luck.