Having issues with my new Melo 3 mini. With a new coil in it it vapes great, loads of flavor and big clouds. After I refill it gets maybe 4 puffs and then the flavor goes away. I find that by unscrewing the fill cap the favor returns for about 4 puffs. Somehow the tank appears to be vacuum locking and not wicking I believe. I've tried 6 different coils including a Ccell. Any suggestions how to fix this?