Keep in mind that recall training, like all training, needs to progress gradually. Starting with getting a reliable recall without distractions, then with distractions in the distance, then distractions closer. Maybe find a place to practice where you can see dogs or people in the distance, but still hold the dogs attention.
And until recall is reliable,
never use the recall command unless you know the dog is going to obey. Every time you use the command and the dog ignores it, the recall becomes more like a suggestion than a command. And you want it to be something that is so practised that coming on recall is automatic, not something the dog has to consider. So in the beginning of any level of training I would take the very good advise from bizzilizzy and make yourself interesting. When the dog is already on it's way towards you, then you can use the recall word. That way the command will be more reliable in the future
Keep training, remember to make the rewards high value. Favourite treats may not be enough to compete with the world around you. You may have to use tug toys or wrestling or running and playing with your dog. The sillier you get, the more fun you are for the dog to obey. And when you have practiced enough you won't need to make a show every time.
10 months is very young still and you will probably need to train for months yet before recall is perfect. In the meantime, the long line is a helpful tool in areas where you need to be in control. Try to find places where you can train without a longline too, somewhere safe
Another good tip is to remember to recall and release, recall should not mean end of fun every time. So getting the dog to give you attention and come on recall, then rewarding by letting him run to other people or dogs is helpful. Maybe best to do this with someone who knows you are training and will not let their dogs come to close and disturb the recall.
Good luck and have fun!
Edit: Just noticed you wrote that he had good recall and recently started "forgetting". So you probably know all the things I wrote
Thought I'd add a well done and keep going! They get a little forgetful in that age, but when they get older and hormones settle they usually remember how to behave again