Dynamic fields return ajax errors

Steps to recreate:

1. Download the latest dev release.
2. Enable Display Suite, Display Suite Extras, Display Suite Forms, Display Suite UI.
3. Navigate to Structure > Display Suite > Fields and click "+Add a dynamic field".
4. Give it a label (I tried many different ones, but "foo" should suffice).
5. Check the Entity boxes for Comment and Node and click save.
6. Navigate to Structure > Content types > [any content type ] > Manage display > Teaser.
7. In the bottom vertical tabs, select One column for the Layout for [content type] in teaser and click save.
8. Move our new dynamic field 'foo' up into the 'content' region.
9. Click the cog wheel for the foo field and click the link 'Select content'.

On localhost where the url is localhost/fooclientsite, I get the following error in a dialog box:

An AJAX HTTP error occurred.
HTTP Result Code: 500
Debugging information follows.
Path: /fooclientsite/admin/structure/ds/fields/manage_ctools/content/add/node/submitted_by_and_links?selection=1
StatusText: Internal Server Error
ResponseText:

On a server where the url is fooclientsite.foodomain.com, I get a different error:

An AJAX HTTP error occurred.
HTTP Result Code: 200
Debugging information follows.
Path: /admin/structure/ds/fields/manage_ctools/content/add/node/foo?selection=1
StatusText: OK
ResponseText: 
Fatal error:  require_once() [function.require]: Failed opening required '/path/to/domains/fooclientsite.foodomain.com//Array' (include_path='.:/usr/local/lib/php:/usr/local/php5/lib/pear') in /path/to/domains/fooclientsite.foodomain.com/sites/all/modules/ctools/includes/plugins.inc on line 779

Any ideas? I'm happy to dig deeper if anyone has a suggestion.