There has finally been an indictment of a Blue House official in regards to the Ulsan Mayor election meddling case:

This file photo shows Lee Jin-seok, presidential secretary for state affairs monitoring. The prosecution indicted him on April 9, 2021, on charges of meddling in the mayoral election in the southeastern city of Ulsan in 2018. (Yonhap)

Prosecutors on Friday indicted a presidential official in a high-profile political scandal surrounding a 2018 mayoral election.

The Seoul Central District Prosecutors Office charged Lee Jin-seok, presidential secretary for state affairs monitoring, with violating election laws, wrapping up more than a year of investigation into the case in which presidential officials and a ruling party candidate’s campaign allegedly colluded to win the mayoral election in the southeastern city of Ulsan. (…..)

In January 2020, a total of 13 officials including Song Cheol-ho, current mayor of Ulsan and longtime friend of President Moon Jae-in, and Han Byung-do, former senior presidential secretary for political affairs, were put on trial in the same case.

Yonhap

You can read more at the link.