How can Kazakiri Hyouka appear in a photograph but not be seen in surveillance camera footage?
Well, she's unstable, so her qualities change every once in as while, making it possible that she was observable by a surveillance camera at one point and not another...

Surveillance cameras may also work differently from photographs, making her able to be seen in the latter, even if her qualities were the same.

Lastly, the surveillance cameras are likely monitored by Aleister, especially the ones in That School, and he erased Hyouka's presence because he didn't want her revealed or something, but a photo camera isn't connected, and so he can't hide her presence there.



If your question is "Why didn't Yomikawa find any info on Hyouka?", perhaps its just because there was no information to find. She's totally new. There wouldn't be much, if any information on her generated in less than a day out in public?