I began vaping with the Halo Triton system and I now also use Nautilus Aspire Mini on an Aspire VV device. I will soon make the plunge and purchase (actually pre-order - an XS Mini - yah, I know, I went from zero to sixty in less than three months

. On and off, I've experienced what you describe; a loss of e-liquid taste or flavour in as little time as it takes to go from a full to an empty tank. I think that perhaps I'm experiencing a form of "vapors tongue" where the taste buds become desensitized to flavours. I always thought that condition only affected people after a considerable amount of vaping the same juice, but I could be wrong. Anyway, what I do to reduce or eliminate the condition is to have two or three tanks filled with different flavours so that as/if one becomes flavourless, I'll grab a different tank and vape that juice for a while. Also, I've found that the taste of your juice may be different
to you depending on the time of day as well as what you might be or had recently eaten or drank. You're kind of limited with the Halo because you have no control over the wattage (voltage) and you're limited to only four different coil resistances. When my flavours begin to fade, I'll sometimes crank up the voltage on my VV device and this will sometimes help. Lastly, I find that the Halo Triton system does a better job at vaping tobacco type flavours and not fruits or desserts. Don't get me wrong, I like the Triton and still use it regularly, but you are somewhat limited. When all I said and done, it doesn't matter what you vape with as long as you are satisfied and, above all, you stay away from cigarettes.
I don't understand why filling up a half empty tank gives you back your flavour? Weird, but I don't believe that it has anything to do with top coil wicking.
Good luck,
Peter