Only Admin (User 1) Can Change a Slideshow's Position or Alignment from Default Settings

I *think* this is an access bug, and not just me missing a config setting somewhere.

When logged in as User 1, every Slideshow-enabled node includes a "Slideshow Settings" batch of form elements in edit mode, right after the "File Attachments" section, so that the default Position, Alignment & Image Size settings can be overridden.

For all other users, however, the "Slideshow Settings" fieldset never appears. Attached images still display as a slideshow, but there is no way to alter the defaults.

These other users have been given Access Control Permissions to:
- Create & edit Slideshows (under Node Module)
- Create & edit other Slideshow-enabled content types (under Node Module)
- Configure Slideshows (under Slideshow Module)
- Upload files & View Uploaded files (under Upload Module)

I've even tried adding "Administer Nodes" and "Administer Content Types" permission (this is not a live production site), to no avail. I also tested on another, bare-bones site install, to make sure some other access-control module wasn't creating a conflict.

So I'm stumped. Is there a permission setting I'm missing somewhere? Or is this a real bug with the $form['slideshow'] access check? Please help.

Thanks!