After beating out some heavy competition (Frank Ocean, The Lumineers, Alabama Shakes, Hunter Hayes) to win the Grammy for best new artist in 2013, Fun. has followed up with something few expected: Nothing.

Despite an out-of-the-blue Facebook update posted at midnight eastern time on Feb. 4 stating that the band "is not breaking up" (worth noting: it arrived after repeated requests on Feb. 3 by Billboard to comment for this story), multiple sources tell Billboard that the members of Fun. -- comprising Nate Ruess, 32, Jack Antonoff, 30, and Andrew Dost, 31 -- are on shaky terms with weeks, even months, going by with little to no communication among bandmates. The cause of the discord? A "clash of egos." The result: a three-way splinter.

Billboard has learned that frontman Ruess has started recording a solo album with producer Jeff Bhasker, who helmed Fun.'s Grammy-winning Some Nights, which has sold 1.6 million albums, according to Nielsen Music. "He's written a lot of songs," says a source, confirming that it will be released by Fueled By Ramen/Atlantic (Fun's label via Warner Music Group), though no timetable is set.

Antonoff, meanwhile, has become the group's most visible member thanks to a well-received solo project, Bleachers, whose Strange Desire ended up on several "best of 2014" lists (of course, ­dating Girls creator-star Lena Dunham doesn't hurt his public profile). Antonoff has been devoting his time to Bleachers, who are signed to RCA, and his songwriting career (recent credits include Taylor Swift's 1989 and a new track by Grimes).

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Multi-instrumentalist Dost has kept busy, too, crafting the score for The D Train, a movie starring Jack Black and James Marsden that IFC recently picked up at the Sundance Film Festival. He also has started playing out on his own and is in talks for a publishing deal, according to another source.

So what does this all mean for the 7-year-old Fun., whose appeal spans teens and adults? Given the massive success of the band's second album, an "extended hiatus," as some groups like to spin their internal squabbles, feels unlikely -- but so does new Fun. music in 2015. (The last time the members were seen together was for a one-song performance on The Tonight Show in June 2014; Ruess has guested on songs like Pink's "Just Give Me a Reason" and Eminem's "Headlights.")

To that, Grammys executive producer Ken Ehrlich offers a silver lining: "[There's] no doubt in my mind that, whether they continue as Fun. or as solo artists, both Jack and Nate have big futures ahead. I loved the Bleachers CD, and I've heard a few tracks that Nate has done, and they're both musically great."

Solo Smash From Fun.'s Jack Antonoff

But when it comes to solo projects from rock bands, conventional logic tends to hold true: They don't sell as well. For instance, the solo album to emerge from Fall Out Boy's hiatus -- Patrick Stump's Soul Punk -- moved just 9,000 copies when it debuted in 2011. The 2010 debut by The Damned Things, a "supergroup" featuring two FOB members and Anthrax's Scott Ian, missed the Billboard 200 entirely. But FOB came back in a big way, selling 154,000 units of Save Rock & Roll in 2013 and 218,000 album-equivalent units of American Beauty/American Psycho, released on Jan. 20. The latter is the band's best showing since 2007.

Ultimately, say industry insiders, it will take a big payday -- like a headlining spot at Coachella, where a band can command around $1 million -- to bring even the worst of former friends back together. The band members clearly take issue with that assertion, declaring in their Facebook post, "making records and touring when its [sic] 'good for business' means nothing to us."