I have had the same probably with KA1 coils when I switched to Power Curves (a setting in Arctic Fox, for those who don’t know). I was using a “Cooldown” Curve, starting with 100% power (33-37 Watts), going gradually down to 75% of that within two seconds (the average duration of my puffs). By using that curve, my coils gunked up and produced a horrible, bitter flavor within about 6 ml of juice vaped. It was so disgusting that I didn’t even bother cleaning it and junked it immediately, but the new one gunked up just as quickly. Before using power curves, with EVERYTHING else the same, I could go for two weeks with same coil and wick, and it still tasted ok. Any explanation for this?
(I switched to NI200 and TC now, no change in taste for three days).