OCSP responds "unauthorized" (0x6) for otherwise valid cert

Two different single domain certificates configured for an Apache 2.4.6 server via mod_ssl, OCSP stapling configured. CentOS 7.1, fully updated. One certificate per VirtualHost (obviously). Firefox refuses to load either site, reporting a “sec_error_ocsp_unauthorized_request” error. Testing the OCSP responder via manual check or SSL test returns “unauthorized” for a reason I have yet to understand.

Disabling OCSP stapling for that VirtualHost allows the site to load with no problems.

The wildcard cert I have on the “main” domain doesn’t have this issue.

Is anyone else having these kinds of issues, or just me?