Well, confessedly without having read above as really over fatigue crushed atm but, as this is a real personal interest to me long time, having never smoked even pure weed since 2008 full 24 365 vaporzing life, I think....
Well 1st, when it is a tobacco smoker, yes def expect vaping pure ganja to induce coughing until tobacco ceases, mostly!
Otherwise still may apply, it takes time in my mind for some it can require full smoking abstinence and inside one month maybe no more vaping coughing.
It's the sheer v powerful instant expectorant action of higher cleaner gassed THC which is culprit.
Good clean 19% or up full profiled minus TH ofc lol CBD flower, may be v different in that respect and IME that stuff vaporized really seems to mellow buzz me up almost like reg herb.