Pokémon Masters EX has confirmed an issue affecting the Sygna Suit Kieran EX Master Fair, with a fix currently scheduled for May 12. The developers acknowledged the problem through an in-game notice and said adjustments are already in progress to address the affected content. While details about the exact issue are limited, players have been closely watching for updates since Master Fair sync pairs are usually tied to major pulls and limited-time banners. The quick response at least signals that the team is actively monitoring player feedback and working to keep the event running smoothly ahead of the planned fix rollout.
Source: Official Pokémon Masters EX site