As of 5.4.2. Passcode photos galleries MUST be set to PUBLISH in order for the passcodes to be found. If the gallery is set to draft, it won't find the photos. It was already like this with scanning QR codes. It now applies to all passcodes entered into the find my photos form.
An issue was brought to my attention with parents accessing galleries with passcodes before the photos were ready while the gallery was set to draft. So I have made it so the gallery must be set to publish to view the photos.
You can batch change the status by checking the checkboxes next to the gallery names (or click Select All) and selecting batch edit at the bottom.
If you don't want the galleries listed on your site, there is an option in the passcode settings 'Do not display with list active galleries on website' if you don't want them listed on the site.
OR you can edit the section your galleries are in and click Layouts -> Page Listing Layout and set the items to show per page to 0.
