I had the same issue with my 2014 Mazda CX 5. The certified mechanics at the dealership told me there was nothing wrong with the vehicle. When I tried to trade in vehicle at another Mazda dealership, I was informed by their certified mechanics, the SUV had issues and they were not interested in a trade. I eventually took my Mazda to a mechanic in my neighborhood and he found a bolt was loose on the engine mount. He fixed the problem and it stopped bucking.
The lesson of the story, not all Mazda dealerships have certified mechanics who stand by the vehicles and know what they are doing.
By they way, before my neighborhood mechanic discovered a loose bolt on engine mount, the Mazda dealership informed me the problem was the clutch system needed replacing. They allegedly installed a new clutch kit, which did not fix the bucking problem. Conclusion, I never needed a new clutch kit replacement. Again, lesson learned.