WWE has just announced via social media that Elias is injured and will no longer be competing in his King of the Ring semifinal match against Chad Gable:
— WWE (@WWE) September 10, 2019
We will have more on the story as it develops.
UPDATE: Dave Meltzer is reporting that this is an ankle injury:
Elias is an ankle injury, the show has been rewritten to reflect the change. Not sure how it's being handled but story will reflect reality.
— Dave Meltzer (@davemeltzerWON) September 10, 2019