Nevermind, reuploading the theme like it was recommended here fixed it: https://support.apollo13.eu/discussion/6236/album-issue-only-one-photo-appearing#latest
Thanks again Daniel, I hope you can use a screenshot in html editor mode? https://nimbus.everhelper.me/client/notes/share/236104/0UFBZ51NPo1PqPCXVo4a4bQ9mMCcbZIQ/