At what temperature did you add the fo to the wax? If you add it at too low of a temperature, it may not be mixing well with the wax. This could leave pockets of fo in your wax as the candle is burning. I usually add my fo at 175 degrees and stir slowly for a couple of minutes until it is well blended. Then I let it cool to the temp I want, then pour into containers. Hope this helps!