Album Navigator shows no items in new galleries

My site has a homepage with a single Album Navigator block. I recently added a few galleries (e.g. “The Hope” or “Ally – Assorted”) to the block and updated others, and now any of the new/updated ones will not show any items when I click on their cover image in the navigator.

The following error is shown in the browser console:

TypeError: Cannot read properties of undefined (reading 'length')
    at i.value (pgc_sgb_albumnavigator.js?   ver=3.1.6:1:201316)
    at i.value (pgc_sgb_albumnavigator.js?ver=3.1.6:1:200569)
    at l.onreadystatechange (pgc_sgb_albumnavigator.js?ver=3.1.6:1:171594)

WP version is 6.4.1, site password is temporarypassword. Each Gallery also has its own page with the Saved Gallery block, which work fine. Album Navigator seems to be the only issue

The page I need help with: [log in to see the link]