Production sources tell us Katy's almost always late to the audition rounds, showing up 10-25 minutes after call time. While it's been frustrating for show producers, we're told the other judges -- Luke Bryan and Lionel Richie -- haven't been all that upset.

There's a bigger issue that looms. We're told the judges are all solid and their chemistry is good. Problem is ... there's no comedic tension a la Paula/Simon or Blake/Adam on "The Voice." Katy is really fun, Lionel has a strong point of view and Luke's pure country. But they're not at each other's throats, either in a serious or funny way, and some honchos are worried that's the kind of heat that makes a show a hit.

As one source said, the editing of the auditions is everything. It could make or break the reboot.