Upon further investigation into the NIST validation error, I discovered that HealthFrame allows for a blank entry for the Start Date of a Condition. This causes the file generated with the CCD plug-in to not include an 'effectiveTime' element for the condition.
Proposed Solution: Include a null 'effectiveTime' element (e.g. <effectiveTime/> ) in the CCD file when a Start Date is blank. This solution should be considered for any element where an entry is required by the standard.