Search result column headers missing after click "cancel" on action

To reproduce on http://dmaster.demo.civicrm.org:

1. Log in, navigate to CiviCRM; navigate to Custom Searches > Postal Mailing (note, this bad behavior also appears on Zip Code custom search, and possibly on other searches; not sure if it's only custom searches).
2. Enter any criteria which will yield results and click `Search`
3. In the search results, check the box for any one or more found contacts; also observe that all search result columns have headers ("Contact ID," "Address," etc.).
4. In the 'Actions' drop-down list select 'Print/Merge document' (i'm not sure if this bad behavior appears with other actions); this opens the 'Print/Merge document' form.
5. In the 'Print/Merge document' form, click the 'Cancel button; this returns to the search results.
6. In the search results, observe that some column headers are missing; comparing the "before action" and "after cancel" images attached to this ticket, you can see that only the "Name" column has a header.

Other notes:

• I've observed this on CiviCRM 4.7.12 as well as in the dmaster demo.
• I checked the JavaScript console and find no errors reported there.