It could be the coils. Kanger and Aspire both went through this with T2 and T3 coils last year and it's not surprising that we are hearing about it again. It could be old coils that weren't recalled in last years admission by the manufacturers that they had a problem. Are they changing taste and finally failing with an open circuit or is it just bad flavor?
As I remember, the T2, Evod, and the Kanger Protank all used (or were compatible with) the same coil. They all had problems like the one you are describing.
If you want to ditch all those and are willing to wind your own coil once every month or two and change the wick twice a week, try a Kayfun or one of the other RBA's. You will be free of the bad coil problem. Sometimes, I can go a week on a cotton wick and replace it during a refill in 5 minutes. The coils dry burn and last a couple of months. A roll of Kanthal and a bag of cotton balls can last you a year for $10.