smells coming into home from neighbours unit

Hello,

I have been having an issue where I am smelling cooking and burning odurs coming from my neighbours semi detached unit. It seems these are travelling through the ducts, I can smell it from the kitchen exhaust fan and on the upstairs level in the bedroom from the floor register and bathroom etc. It's becoming a big problem as the cooking is done several times throughout the day.

I have to keep my kitchen exhaust fan on continually to clear the odor out my house. I've tried portable air filters, spray, blocking off the kitchen exhaust and it doesn't seem to help.

I've had an inspector check it out and he says he cannot determine why it could be happening. He checked the attic and could not find an issue.

Please help if anyone has any suggestions or heard of this.

Thanks