Strange stuff,
The only problem I've ever had was leaving the Dominican Republic, security confiscated everything that looked like it was worth something. They didn't seem to have any interest in ego/ce4 / cheap looking gear, they let about a dozen through before & after us, in plain view of everyone around. we won't be going back.
Other than that, I fly domestic & international frequently, been carrying vape gear with me since 2011, never had a strange look, question, delay or anything confiscated.
Just me, I haven't been on an airline that doesn't allow batteries in carry on, I always remove batteries from device & put them in hard plastic battery cases.
I know several folks that have had trouble with Mx, all were carrying large amounts of liquids & other various vaping gear.
Like 5 - 20 120mls & dozen new tanks & power devices in checked baggage, no batteries.
They've cracked down on amounts that can be considered importing with intent to sell.
I go with 5 30mls, 2 power devices, 4- 6 batteries in carry on, never a problem.