Yes, that was the phrase . I want to say Thursday and Monday. It was Costa’s newsroom tag to his package.
Okay, I just went through 14 days (January 28 through yesterday) of the CBS Evening News.
On the CBS Weekend News on Sunday, Willie James Inman had a follow-up on the seizure of election records in Atlanta. There was a soundbite from a newsmaker that Trump couldn't admit he lost, but that was not from Inman or any other CBS talent. CBS News Election and Law contributor David Becker said "disinformation was being spread by the president".
On the CBS Weekend News on Saturday, Inman covered the Trump social media post with the heads of the Obamas on the heads of apes. Trump has said the video was about election fraud, but the CBS story on Saturday didn't reference that.
Last Wednesday (2/4), Weijia Jiang covered the seizure of records in Atlanta and used the phrase "President Trump continues to insist the 2020 election was rigged."
Prior to that, the last CBS Evening News piece involving Trump and elections was January 29, the day after the seizure. There was a quote about "no evidence that the 2020 election was rigged", but that was from a newsmaker, not Costa, who did not appear in or adjacent to the story, nor from any other CBS talent.
On January 28, in a live tag regarding the seizure, Scott McFarlane, CBS News' Justice Correspondent, said "Trump continues to make baseless claims about winning Georgia in 2020."
So, none of those were Costa, and none used the phrase "continues to lie", and yes, there is a BIG difference between the phrases used and that one, as "lying" implies willingness to deceive and a knowledge that the facts are other than what you're saying while "baseless claims" and the others don't make a determination of motive, just a statement of fact.