There is some yeast suspended in all non-filtered beer, to my understanding. I don't think off flavors could be coming from that. Some commercial crafts go to great lengths to bottle condition with yeast, believing it makes a better end product. Three batches in, there are still tons of variables in your process. My first thought is always fermentation temps, unless you have controlled fermentation, this is likely the largest variable in flavors when doing a kit.
Give a man a beer, waste an hour. Teach a man to brew, and waste a lifetime! Bill Owen quote
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