OLYMPIA — A technical problem was affecting the mailing of up to 21,000 ballots in Washington, and some voters who registered online may not be getting a ballot at all, officials said Monday just hours before an election headlined by contentious initiatives. The voters impacted are those who recently used the Department of Licensing website to update their address or register to vote, according to the secretary of state’s office. Officials said voters who are registered but haven’t received a ballot should go to elections offices and cast a provisional ballot. Those votes must be completed by the close of business Tuesday. The secretary of state’s office said it has not been receiving online voter registration updates from the Department of Licensing and just learned of the problem Friday. But licensing officials said they have been forwarding all the appropriate information since the online update option was implemented in August. “We believe it’s really important to get it right, and we believe we did,” said Gigi Zenk, a spokeswoman for the licensing department. Katie Blinn, the co-director of elections in the state, said licensing was switching to a different method for sharing the information but the secretary of state’s office had indicated it wasn’t ready to start using that method until after the election. She said the office didn’t even know that this was an option on the licensing website. “Obviously, there was a miscommunication,” Blinn said. The secretary of state’s office estimated that about 14,800 address updates were not received. Some county elections offices may have received the address changes through other means. The post office may have forwarded some ballots to the new addresses, officials said. Another 5,900 people updated their information on the licensing website but were not registered. The secretary of state’s office said those people will be asked for further registration information and can cast a provisional ballot in the meantime.