Toronto Wolfpack prop Darcy Lussick has been refused entry to the United Kingdom by the UK Border Agency following a trip to mainland Europe.
Australia-born Lussick, 29, was returning to the Wolfpack's British training base in between games.
Majority owner David Argyle said the Championship leaders were "frustrated" by the decision.
He added they had "followed protocol in place between our governing body (RFL) and the Home Office".
Lussick, whose brother Joey plays for Salford, will join up with the Wolfpack in Canada for their next home game against Dewsbury on 15 June.
"Managing immigration and work permits are just part of our journey," Argyle continued.
"All protocols will be thoroughly reviewed, and we will ensure that the UK Border Control remain informed of any changes.
"The welfare of our players and coaches is always our top priority and we are going to continue working to make sure that the immigration process becomes easier moving forwards."
Toronto are six points clear of second-placed Toulouse as they bid for a place in Super League for the first time.