Lapis didn't put too much effort when he was checking on the activities of both Gong Sun and Feng Huai. The two weren't too discreet about their actions, seemingly as if the two of them weren't even afraid of being found out. Or perhaps, because of their relationship as brothers-in-law, no one would have thought that the two men were thinking of sabotaging a rising entertainment company for their own gain.
At first, when Lapis was getting more and more evidence of Feng Huai's betrayal towards Ran Xueyi, he accidentally stumbled upon Gong Sun's unfaithfulness.
He found out that Gong Sun has been collecting projects and resources that Dauntless secured a while ago and leaked it to their competitor's companies. This kind of movement wasn't too obvious because Gong Sun only leaked it once in a while and he did it in a way that no one would ever suspect him of spreading company secrets to others. He must have believed that no one would ever investigate him.