That's actually 2 separate things as far as I know.
First thing first, how you think some camps ignore you after you Q, that's not entirely true. They will only ignore you in animation but in reality they're still attacking you, it's just sometimes after Alpha Strike, jungle monster's models would be stunned but their damages are still calculated corrected. So treat that as minor graphics bug.
In the case of Dragon. If you use Alpha on it to initiate the encounter, it would reset immediately. That's why the thing to do is walk in, AA the Dragon and back out right after hitting the blow (you should be able to dodge the knockup that way, given if your MS isn't too low, not sure if tier 2 boots is a must here though never officially tested it). Once it's already up in the air and coming for you, use Q at your leisure. That's how I do it anyway.