On September 13, VIXX's management agency Jellyfish Entertainment posted an official statement on VIXX's fan community.

We are writing this to inform you that VIXX LR's planned schedule for M.Net's 'M!Countdown' tomorrow has been canceled.
Leo said that he has stomach pain this evening, so he immediately went to the hospital for treatment.
In order for him to undergo further examination tomorrow and get some rest, the performance for 'M!Countdown' is canceled.
We ask for your understanding for this sudden notice, and we will provide more information on VIXX LR's upcoming schedule later. Thank you."

Get well soon, Leo!
(Credit= 'RealVIXX' Facebook)
(SBS Star)