After refusing for weeks to detail the extent of back-end problems with healthcare.gov, the Obama administration on Friday said a technical bug affected approximately 25 percent enrollments on the federal exchanges in October. Those technical bugs, separate from the troubles consumers had experienced accessing information on the website during the first two months, are posing a significant new problem for those who signed up and are expecting insurance coverage come Jan. 1. One in four of those applications either did not get transferred to insurers, were transferred in duplicate form, or had major errors in information shared. Insurers are supposed...