According to an official announcement by Pledis Entertainment on June 30, it seems Seventeen's Vernon has suffered a leg injury during Seventeen's solo concert 'Ideal Cut' in Seoul. 

"Hello, this is Pledis Entertainment. We would like to notify you regarding Seventeen member Vernon's injury and concert attendance. 

On June 29 during the last stage of the '2018 Seventeen Concert - Ideal Cut' in Seoul, Vernon suffered from a leg injury and sought out medical help, after which he received treatment including orders to wear a cast, etc. 

As a result, we determined that it would be difficult for him to carry out a show over 3 hours long; however, Vernon's desire to stand on stage for the fans who waited for him despite the label's discretion was so strong, that he will ultimately be performing on stage during the remaining two concert shows on June 30 (today) and July 1.  

However, because Vernon is in good condition and suffers no other abnormalities other than his leg injury, he will be sitting in a chair for various performances which include a choreography, while sitting out for other select stages. 

We ask for your understanding, and vow to do our best so that Vernon may successfully wrap up his remaining stages while maintaining his good condition and without further harm. 

Once again, we apologize to fans who waited a long time for Seventeen's 'Ideal Cut' concert, for causing worry. Thank you."