It just goes to show how many airlines do this, I had a BMI flight cancelled last month because of operational reasons (they got the plane due to operate my flight stuck somewhere the night before) I put in a EU261 claim and they said it was a manufacturing issue so I wasn’t due it. I replied saying by manufacturing do you mean a technical issue with the aircraft and referenced previous legal rulings before threatening my own. They then replied saying they’d re-considered and awarded me the compensation.
Just goes to show in both cases have some background knowledge and don’t give up when they try and fob you off.