First off - never, ever, ever think that giving treats for knowing status is a viable or productive thing! ( I know you don't, but don't start to question yourself on that!)
Madness and a total misunderstanding of all things canine from that person!!!!! ( If you see her again though, just out of interest, ask her how she heard of that idea, would you? I will bet either a behaviourist***** or a trainer! **** was to say that some are qualified and a great many are not!!!)


On to your actual problem. I am assuming that your little bitch has run with, more or less, the same group of dogs at the puppy creche?

If that is true then it won't matter how submissive she is, I'm afraid, the pack structure has to be realigned as she becomes sexually mature. At six months old she has the potential to become a breeding female. This does not mean she is coming into season, although you should keep an eye out from now on, but that she has the potential to.
The other dogs have treated her as a puppy up until now but she is changing physically as well as hormonally and has to find a place in the pack as an adult rather than a pup.

Remember our domestic dogs retain the puppy characteristics into adulthood, GR's more than many, so although we see a pup other canine pack members see a threat to position. If it is an easy target, such as a submissive little bitch, everybody will get their claim on a higher status as soon as possible. When one starts pack alliances come into call and it seems all gang up on one, unprepared individual.
In wild canids such a submissive animal would probably not survive. We have bred animals to exhibit this characteristic.

Taking her to a new area with new animals will help in the short term, but, eventually the same situation will develop if it is the same dogs all the time.

I suggest you take her out on her own sometimes, to the dog creche less frequently and to as many new areas as possible. You are her pack and she doesn't need to socialise on a daily basis with the dogs at the creche. But she has to fit into a pack she is confronted with every day. In a way, she will have to learn to deal with it and take her place in that pack if she is part of it.
Try to remember that it is a lot of noise, looks horrid but no real damage is done. It really is a natural process and she is coping well by submitting to it, imagine what it would be like if she did stand up for herself and fought for her place!!!!!