In states including California, Nevada and Massachusetts, which are running their own online insurance exchanges, some consumers picked a private health plan and paid their premiums only to learn recently that they aren’t insured.

Others received a policy but then got married, had a baby or another “life event” that required their coverage to be updated, yet have been waiting months for the change to take effect.

As a result, some of these people say they have put off medical treatments or paid out of pocket for health expenses. Some insurers say they will be reimbursed.

The Obama administration said in April that about eight million people had picked health plans through the Affordable Care Act, using online exchanges where they compare prices and see if they qualify for credits to subsidize the cost.

There are no hard numbers on how many consumers have experienced coverage issues. Out of eight million enrollees, the number appears to be a tiny fraction.