The 26-year-old hasn't contacted his family for months, and didn't see his two young children for Christmas.
Older sister Sunni Tindal said the behaviour was very out of character, as he normally visits his kids regularly.
"I've been beside myself," she told reporters in Cairns on Wednesday.
"We are concerned for his safety, and we just want him brought home.
"Joss, come home. We love you and we need you home... we've just lost another brother and we can't lose another one."
Police say the father-of-two was last seen in Grafton Street, Cairns on November 23, at which time he was in a "physical altercation" with another man.
Joss is 180cms tall with a proportionate build, short black hair and a goatee beard. Joss has two large tattoos - one on his neck, and a rose tattoo on his arm.
He is known to frequent the Cairns and Townsville areas, previously working as a busker in the Cairns Esplanade and CBD. He also has contacts in the Cloncurry area.
Cousin Jodie Cockatoo described Joss as an avid musician who's "very loyal to his family".
"It's been quite a long time now, so we're trying not to think of anything no good," she said.
"We're just keeping our fingers crossed and hoping and praying he's going to give us a call soon."
Joss is one of four men missing in Queensland's far north since late 2017. Police say all four men are missing in unrelated circumstances and their disappearances aren't linked, but they hold serious concerns for the safety and wellbeing of each of the men.
“Police throughout the region have conducted extensive enquiries, and in some cases, land and air searches, for the men, and to date we have not found any trace or indication as to their current whereabouts," said regional crime coordinator Detective Superintendent Glenn Kachel.
Anyone who may have any information which could assist police with their investigations is asked to contact Policelink on 131 444 or Crime Stoppers on 1800 333 000.