Its only my opinion but you don't really need an ohm reader for those kinds of
coils unless you're just curious.
I'm betting you vape on a variable device right? Perhaps wattage mode? if that's the case then anything you build between a 1.8 to a 2.5 will fire the same because of the power setting.
As for the flux: something is not tightened down properly. Generally on a larger Atomizer, like a genesis or a dripper. If the numbers run its means the terminal connections aren't tight.
So usually re-tighten. Then screw the coil onto the meter securely it does not have to be all the way down. 2/3 to 3/4 down is secure enough. The flip the switch. Kanger
coils shouldn't have this problem at all. so if it continues regardless of kanger or a solid dripper build. Something is wrong with the internals of your meter. Nothing wrong with the Sigelei brand, I would just assume bad luck and ask for a replacement.