As Lukaku prepared to take a penalty during the game, racist chants could be heard from a section of fans behind the goal, and Lukaku responded by calling on footballing officials to do more in the battle against discrimination.
Serie A launched an investigation into the incident, but BBC Sport have revealed that a judge has ruled that there was not enough evidence to punish Cagliari.
The report did acknowledge that chants and whistles were directed towards Lukaku, but the judge, incredulously, decided that the abuse was not serious enough to justify imposing sanctions on the club.
However, Cagliari were fined €5,000 for throwing plastic bottles onto the pitch against Parma on Sunday.
This is just the latest incident in a long line of problems which have left fans around the world baffled at Serie As lack of commitment to tackling racism. Cagliari themselves have been investigated on multiple occasions for abusing the likes of Sulley Muntari, Blaise Matuidi and Moise Kean, but have avoided punishment every time.
An Inter supporters group even wrote to Lukaku after he was abused to claim that the chants were not racist, incredibly insisting that the abuse was more of a sign of their respect towards him as a footballer.
Inter themselves do not have a clean track record either. Back in December 2018, Kalidou Koulibaly and Carlo Ancelotti spoke openly about racist abuse during a game between Napoli and the Nerazzurri, but again no punishments were issued.
Senior players like Lukaku and Koulibaly have pleaded with authorities to improve their stance on racism. Lukaku claimed that it almost feels like the world is going back in time, and he begged for a suitable solution in the very near future.