CB Auto-Action Internal Users URL not working

Joomla 2.5.18
CB 1.9.1
CB Auto-action: 5.1.3
PHP 5.4

We've setup several auto-actions that are working as expected, but I need to run an auto-action against all users in a specific user group. I added the InternalUser trigger to the auto-action and then browsed to the unique Internal Users URL found in config but I only see a blank page. The auto-action is not executing as I can check my users' profiles and see that the expected change has not occurred.

Update:
I enabled debug mode for the auto-action and set Joomla error reporting to maximum and now I see a page full of the following when I execute the Internal Users URL:

"string(73) ":: Action 30 :: Access check for 62 failed: looking for 859 in -1, -5, -3" string(73) ":: Action 30 :: Access check for 72 failed: looking for 859 in -1, -4, -3" string(74) ":: Action 30 :: Access check for 134 failed: looking for 859 in -1, -5, -3" string(74) ":: Action 30 :: Access check for 406 failed: looking for 859 in -1, -5, -3" string(74) ":: Action 30 :: Access check for 425 failed: looking for 859 in -1, -4, -3" string(74) ":: Action 30 :: Access check for 105 failed: looking for 859 in -1, -5, -3" string(74) ":: Action 30 :: Access check for 106 failed: looking for 859 in -1, -4, -3" string(74) ""

You have the action setup to loop through your entire database of users and check their usergroups. A lot of them are going to fail as the debug message is outputting. The Internal Users URL is always a blank page, because it's a CRON endpoint. When an action fails it's usually the Conditional. Please provide a screenshot of your entire action configuration.

Thanks for the response! There is not a condition on the auto-action, only an Access set to the group I need the action performed on. The Type is "field". So, the auto-action is suppose to set 'fieldA' to Yes for users in 'selected_group'.

There's nothing I can do unless you provide a screenshot of the action so I can review its entire configuration. Also keep in mind you can't save a user object that is an administrator or above while not logged in. In other words your action can't edit administrators.