It is nerves from him and not aggression. He is a year and rather sensitive.
Fantastic recall and wait etc.
But if out on walks off lead (forest type place) it is random. Some people and dogs he doesn't bark at and others will bark (never gets closer than 4 metres)
Saw a horse yesterday and made him wait and sit and have treats and he was fine then let out bark still
I call away and he comes or I use tennis ball to distract and that works but I've not been able to stop the initial barking.
I use gentle voice and reassurance with him.
Any tips that have worked for you?