From Wikipedia Planet Nine#Citizen science:
In April 2017, using data from the SkyMapper telescope at Siding Spring Observatory, citizen scientists on the Zooniverse platform reported four candidates for Planet Nine. These candidates will be followed up on by astronomers to determine their viability. The project, which started on 28 March 2017, completed their goals in less than three days with around five million classifications by more than 60,000 individuals.
But it has not been updated for nearly 3 years. Is there any follow up study that confirm what these 4 candidates actually are?