Solomona scored 40 tries in the 2016 season, including a record total of 40 in Super League.
Tigers chairman Steve Gill said in October that the 23-year-old Samoan was not for sale and would be returning to the club on 7 November.
BBC Sport understands Solomona has held talks with rugby union side Sale.
The Premiership club declined to comment on the story.

They'll headline the British Summer Time festival on 20 June.
The band, who got back together for a pair of reunion shows in the park six years ago, join Taylor Swift, Kylie and The Who on the bill.
Speaking at a news conference in a London Chinatown restaurant, frontman Damon Albarn joked: "I love it because I can cycle to work".
They'll be the only band ever to play Hyde Park four times after this performance.
Bassist Alex James says that "since we made our last record as a four-piece we have probably only done 20 gigs.
"So for me every time we play together it feels special but in order to keep doing it we need something news to do."
Blur are also working on their first studio album as four-piece in 16 years, The Magic Whip.
Guitarist Graham Coxon said they started recording in Hong Kong when a gig was cancelled.
He said: "we thought we'd put a few days, five or six days, to good use".
The album is influenced by the band's time in Far East.
Damon Albarn confirmed one song was about time he spent in North Korea: "it's my impression of the place, in a very abstract veiled way.
"When you listen to it is pretty self explanatory what it's about".
The singer also said it was nice to work with a basic set-up when they first started to make the album to see what they could create.
He told the news conference that "we didn't have much stuff so it was like recording when we first started doing stuff.  It was a really small studio, it was really hot and claustrophobic.
"We just went in there and knocked about some ideas."
The album will be released on 27 April.
Follow @BBCNewsbeat on Twitter, BBCNewsbeat on Instagram and Radio1Newsbeat on YouTube

The Tonga-born flanker or number eight won 17 Test caps for the All Blacks between 2005 and 2008.
In 2012, it was reported Lauaki - who played for Super Rugby club Chiefs as well as French sides Bayonne and Clermont - had been suffering from heart and kidney problems.
"The thoughts of everyone are with the family of Sione Lauaki. Gone too soon. RIP, Wax," tweeted the All Blacks.
The Chiefs were playing in the Brisbane Global Tens rugby tournament on Sunday and dedicated their victory to their former player.
"We lost a brother today,'' outside back Shaun Stevenson said after the Chiefs won the Brisbane title.
Earlier in the day, Chiefs coach Dave Rennie said his side would dedicate the to the tournament to the memory of Lauaki.
"There's a number of guys who played a lot of footy with Wax,'' Rennie said, referring to Lauaki's nickname. "There's a lot of motivating factors. Not everyone knows Wax, but he played a lot of footy for the Chiefs and he's certainly highly respected among his mates.''
This content will not work on your device, please check Javascript and cookies are enabled or update your browser
Castleford Tigers are to take legal action against winger Denny Solomona after he failed to return to the club for pre-season training.
[NEXT_CONCEPT]
Blur are heading back to Hyde Park with their first album in more than a decade.
[NEXT_CONCEPT]
Former New Zealand forward Sione Lauaki has died at the age of 35.