Often times, pushing down on a dog's butt will do little more than produce an "opposition reflex". That's where the dog pushes back, but in the opposite direction. More simply put, they resist.
If you're luring and the dog doesn't get it on the first attempt, sometimes a subtle shift in context is all that is required to succeed. ie: try moving forward a bit to a different spot or face the other direction, and try again. If that doesn't work, try another behaviour that the dog knows well and will succeed at, in the interim, then immediately come back to the sit.
Outdoor recalls should be built by gradually increasing distance. Start by being very close. This will help to remove the option of non-compliance. Keep the puppy on a continuous reinforcement schedule (one-for-one). Restrained recalls may also help.
'Rattling the treat cup' is something to avoid, unless you want that to become the recall cue, and I'm almost sure that's not what you want. Looks kinda funny to the neighbours, lol, and also has a deterimental effect at the dog park.
'Waiting it out' is not providing any consequence for non-compliance. I'd rather go out to where the puppy is, and engage them in a fun bit of THEM chasing ME back to the door. While not ideal, I think it's the lesser of two evils, ... at least until a firm foundation can be built.
