The Obama administration acknowledged Wednesday that problems persist on the back end of HealthCare.gov, which transmits applicants' information to insurance companies.
In a joint statement with insurers, federal health officials said they were working closely with the industry to "resolve back-end issues between health plans and HealthCare.gov" and would report on their progress at a later date.
The administration has received strong criticism for failing to disclose the error rate for forms known as 834s, which send information about ObamaCare enrollees to health insurers.
The administration's failure to disclose the error rate has led to a series of tense exchanges with journalists on a daily conference call.
The Centers for Medicare and Medicaid Services (CMS) said this week that it addressed a single glitch apparently responsible for 80 percent of the problems. But insurers begged to differ, saying they were still receiving garbled and incomplete data as of this week.
The 834 problem works against the narrative that the federal enrollment website is running smoothly following the administration's self-imposed deadline for most repairs.
If unresolved, it will hamper new policyholders from using their ObamaCare coverage in January, threatening the White House with another major controversy over the rollout.
Wednesday's statement was released jointly by the CMS, America's Health Insurance Plans and the Blue Cross Blue Shield Association.
The groups called the back-end repair effort "very focused" and "driven by a team of experts" from both the CMS and private contractors.
Journalists disparaged the statement on Twitter, suggesting the administration was stonewalling.