After the small rift that happened last night because of the public opinion manipulation stunt that the other entertainment company employed, the whole internet was thrown in a momentary buzz and solely targeted Hera.
Leo and the other male leads were baffled by the sudden targeting of Hera, especially since the issue appeared to stem from a simple disagreement within the show. Despite their investigations yielding no evidence on their end, Leo suspected that someone behind the scenes was manipulating events to target Hera.
This is also the reason why Leo had to use Hera's fanbase to investigate and act, it is so he won't alert whoever is behind it and he was sure that the others also did their own investigation but found nothing so they thought that Leo had a clue and wanted to join the group he had created for Hera.