One of world rugby's biggest and marketable female names, Woodman-Wickliffe had agreed to join the Newcastle for 2025 in a major boost for the club.
The Knights have been attempting to have the 33-year-old's deal registered since last year, but hit a stumbling block with NRL bosses over her ambassadorial roles.
AAP understands the sticking point was a pre-existing deal for Woodman-Wickliffe to be an ambassador at this year's Rugby World Cup in England.
League bosses pushed back on the plan, which would have seen Woodman-Wickliffe leave the NRLW for a week late in the season to be at the World Cup promoting it.
The winger was eventually told the contract would not be registered unless plans or timelines changed, and Woodman-Wickliffe has since given up hope of making the switch to the 13-woman game.
Woodman-Wickliffe's arrival would have loomed as a significant boost for not just the Knights after several high-profile exits, but the NRLW as a whole.
The New Zealander is a two-time Olympic gold medallist in sevens and two-time Rugby World Cup winner.
The flyer was named the World Sevens player of the decade for the 2010s while also being picked in the World 15s team of the decade.
The leading try-scorer in world sevens until earlier this year, Woodman-Wickliffe is a global ambassador for Mastercard who are a major sponsor of the World Cup.
Woodman-Wickliffe would likely have stood to lose money to give up part of her ambassadorial deal to play in the semi-professional NRLW.
There had been an argument that Woodman-Wickliffe's situation was not overly different to several other instances of players featuring across multiple codes in the NRLW.
Knights winger Sheridan Gallagher players for the Newcastle Jets in the A-League Women during the off-season, before switching back to NRLW in season.
Tyla King, Stacey Waaka and Tenika Willison all played for New Zealand in sevens during last year's Olympics, before featuring in the NRLW from round three and four.
But the NRL is believed to view those cases as different, given they are either out of contracting periods or before contracts started for the sevens players last year.
It's thought the league may have been open to Woodman-Wickliffe completing ambassadorial work, had it fallen outside of the season.
But ultimately that could not be agreed to, leaving the NRL concerned that leaving mid-season and in-contract to promote a rival code could set a precedent
The blow to the Knights comes after the 2022 and 2023 premiers lost the NRLW's best player Tamika Upton and captain Hannah Southwell to Brisbane and St George Illawarra respectively.
