I got my first burnt hit today on an Atlantis coil... Was having trouble with my Nautilus O rings and my tank did NOT want to come off from the base. After about 20 minutes of struggling... looking up stuff.... reading the manual, I did manage to reassemble but by then I was cranky and didn't prime it well enough. Blegch. Burnt plastic/cotton.... My first fires are usually tiny and looowww watts, so I didn't scorch the coil completely, but it wasn't excellent. It's vaping fine now, but this only increased the idea of backups, as had that happened to me outside of the house, with no backup, I probably would be smoking. Right. Now.
If your coil isn't burnt, you might want to try a disassembly/cleaning, checking that everything is in place, it sounds like something to do with your airflow, possibly, if the coil is working part of the time? But I don't own that device so I couldn't say for sure. Best of luck with it. It could ALSO be a bad coil, that isn't wicking properly, even though it tastes OK?
Anna