My first Lab, Bess, came to live with us at 5 weeks age -- FAR, FAR too young I soon realized.
We had no other dogs to play with and I'm sure, as a consequence, Bess's identity became that of people -- she loved people, loved to be beside them, schmoozing them and she ignored dogs.
Other dogs would try to interest her in playing with them, say when she was retrieving training dummies I'd sling for her, and she often gave them a body slam that sent them tumbling, until they gave up on her.
Whenever another dog came near us, she often gave the other dog a glance and then looked at me quizzically as if asking, "What IS that thing? Make it go away."
She's 10 months old, and doesn't have many opportunities to interact with other dogs. I live in a very small town so the only opportunity to socialize with other dogs is going camping on the river (not my thing at all) with friends. Our only park doesn't allow dogs, so I'm limited as to what I can do. But, I will start doing some play-time planning with our other friends who have dogs. Hopefully that will help. Thanks so much for your advice.
That MAY help and is well worth trying.
If I remember correctly from Scott & Fuller's "Genetics & the Social Behavior of Dogs"
-- probably the most important dog book ever written (it has much research and elucidation of early developmental critical periods in dogs) -- much of that social learning needs to take place before 25 weeks age to be most effective. But, as Felix described his Laika, perhaps your Maggie can also find some dogs she can learn to like and play with. The effort is worth it.
Having gone through that earlier experience with Bess (& having read S&F's book), when I got Puff, I was conscientious in giving her much experience as a puppy playing with other dogs.