Always link to the upload in question.
https://www.pokecheck.org/?p=detail&uid=9866497
Was captured on a Saturday in a Sport Ball -- Bug Catching Contest
ESV Slot 1: 20 - 39
72100276 seed (frame 474); doesn't have this ESV (only 2,7,2), which is why it is flagged.
BCC encounter slots have never been 100% documented (RNG Reporter notifies users of this) so you can assume it's legal if you captured it. It's just not big enough of a deal for a thorough investigation/fix... BCC errors might be changed to a non-red message in the future.