I have one who will bark at anything that looks like cat, or might be cat, or could be cat in the next county. :(
She also loves being outside in the summer. Sooo
She barks I call her in, no reward, no stimulation. She then has to WAIT to be allowed out again. Not too long for the first barks but getting longer if I have to call her in repeatedly ;) It works for me, she soon gets the idea that barking means boring ;)
She does bark at the Rag and Bone man, but that's OK. I want them to know we have noisy dogs, things were going missing in people's gardens on a Monday.
I'm doing the same with the WeeOne. She would bark at ANYTHING in the house. If OH went to the loo, she'd go ballistic when he came out. If he went outside and came back in, same story, it was beyond a joke. So I decided that I would be a STUPID HUMAN and get her message wrong LOL From then on, EVERY TIME she barked for no reason (ie no-one trying to break in, no-one trying to kill us all with machetes, no cold callers etc.) then she would either be put outside alone

or into the back porch alone

for 5 minutes (eternity for her ;) ) It's working :-D OH just came in after being in his workshop for hours and she didn't bark at all :-D :-D
Maybe you're giving too many rewards and confusing her ?
Hope this helps