perch_blog_categories only showing a single category

Perch: 3.1.3, PHP: 5.6.21, MySQL: 5.5.59, with PDO
Server OS: Linux, cgi-fcgi
Installed apps: content (3.1.3), assets (3.1.3), categories (3.1.3), perch_blog (5.6.1), perch_forms (1.12)
App runtimes: <?php $apps_list = [ perch_forms, perch_blog ];
PERCH_LOGINPATH: /cms
PERCH_PATH: /nfs/c11/h03/mnt/198028/domains/biddlesport.holmesbrand.com/html/cms
PERCH_CORE: /nfs/c11/h03/mnt/198028/domains/biddlesport.holmesbrand.com/html/cms/core
PERCH_RESFILEPATH: /nfs/c11/h03/mnt/198028/domains/biddlesport.holmesbrand.com/html/cms/resources
Image manipulation: GD
PHP limits: Max upload 99M, Max POST 99M, Memory: 99M, Total max file upload: 99M
F1: 3b606135b33e6a102526838f4152a807
Resource folder writeable: Yes
SCRIPT_NAME: /cms/core/settings/diagnostics/index.php
REQUEST_URI: /cms/core/settings/diagnostics/
DOCUMENT_ROOT: /home/198028/domains/biddlesport.holmesbrand.com/html
HTTP_HOST: biddlesport.holmesbrand.com

I am using perch_blog_categories(); to output a category list on my blog. I'm just using the default category.html template. I have created three categories within the same set (blog), but only the first is being displayed.

Has anyone seen this before?