There was a time when Alexander Payne was, as far as the critical majority was concerned, close to unassailable in the ranks of modern American auteurs. His 1996 debut, Citizen Ruth, earned only a niche following, but the five features that followed, from 1999’s sourball classroom satire Election through to 2013’s mournful father-son comedy Nebraska, earned him a reputation as a kind of jaundiced observational poet of sad-sack America, a body of work bound by grim-faced humour, mundane tragedy and white male heroes with scarcely any heroic virtues at all. It’s a run that has netted him two Oscars, a flood of other honours, and repeated critical comparisons to Billy Wilder, Preston Sturges and even John Updike. David Thomson himself gushed: “Payne is one of America’s quiet and persistent treasures, like maple syrup, the St Louis Cardinals or the apparent tranquility of our deserts.”

Yet all hot streaks must come to an end, and Payne’s first film in five years, Downsizing, has landed him in unfamiliarly tepid territory. It looked promising from the outset. Payne’s first foray into fantasy is his most conceptually ambitious work to date, its absurdist premise – what if ordinary people could permanently shrink themselves to Mrs Pepperpot proportions for financial gain? – giving way to a host of more substantial questions about community, social consciousness and economic desperation.

Reviews started strong: it opened the Venice film festival to a raft of raves and “masterpiece” claims, though the opposition formed early. When it travelled to Telluride and Toronto days later, the temperature of the reception plummeted several degrees; the dreaded word “problematic” started getting thrown around by critics doubtful of the film’s liberal political integrity. The chill steadily sapped away at the film’s awards buzz: when the Golden Globe nominations were announced earlier this week, it scored but a single bid for supporting actress Hong Chau, failing to place even in a best comedy/musical field that found room for the Hugh Jackman campfest The Greatest Showman. What did Downsizing do wrong?

Once again, the film itself is a case of promising beginnings, swiftly undone. As someone who hasn’t been in the Payne fanclub for several years, I found myself unexpectedly tickled by the first act of Downsizing, which sees the director – beginning proceedings in the dun Nebraskan nowhere that has backgrounded most of his films – laying out his lunatic sci-fi premise with a dry, droll matter-of-factness and attention to daft visual detail more akin to Spike Jonze. Matt Damon and Kristen Wiig’s gormless suburbanites observe the growing national trend for “downsizing” (a medical shrinking procedure that leaves patients inches high, with vastly reduced costs of living) before taking the plunge themselves; Payne illustrates the dreary practical concerns behind their decision, and the prefab luxury of the miniature midwestern McCity that awaits them after the procedure, with a ruthless specificity that plays to his coolest instincts as a middle-American satirist. We laugh at the vulgarity of “downsizing” culture, which as oddly recognisable as it is fictionally outlandish, even as we wonder, fleetingly, if we’d follow the same herd for the sake of 9,900% increase in the value of our assets.

A natural misanthropist, Payne is at his best when dwelling on the craven weaknesses of consumerist society – masculinity, in particular – that sets its material goals higher than its spiritual ones, gleefully taking in the spectacle of people literally wasting themselves away to gain a lifestyle of dream kitchens and country clubs. (There are environmental benefits to the shrunken life too, but no one seems especially excited about those.) It’s as dispassionately perceptive and witty as the war of petty institutional power structures that fuels Election (still Payne’s greatest film by a country mile) or About Schmidt’s doleful dissection of a life lived in pursuit only of comfortable retirement.

Udo Kier. Matt Damon and Christoph Waltz in Downsizing. Photograph: George Kraychyk

It’s when Downsizing attempts to go warmly humanist on us that it becomes sorely unstuck. Damon’s schlubby everyman Paul finds downsized life no shorter on ennui or existential aimlessness than before: his romantic and professional circumstances take a drastic dip alongside his property portfolio. Yet when his path crosses that of a disabled Vietnamese refugee Ngoc (Chau), a political dissident shrunk against her will as punishment for her liberal provocations, his problems are put rather bluntly in perspective; cue a moral awakening dramatised with a sledgehammer touch, as Paul, his eyes opened to a downsized but nonetheless sprawling underclass, is invited to heal the world one charitable gesture at a time.

Which is all well and good, but for a film hinged on one man’s realisation that the world doesn’t revolve around him, Downsizing itself never shifts on its axis or allows another character to come fully into focus. The enlightenment of Damon’s privileged white hero is supposedly inspirational, but Payne and Jim Taylor’s dense, shaggy-dog screenplay is so wincingly ungenerous to Ngoc – a strident ethnic stereotype, embodying little more than victimised goodness, whose pidgin English is milked repeatedly for laughs–— that his new perspective is never meaningfully tested or challenged. Chau, evidently the film’s last Oscar hope, essays the role with valiant good humour and flashes of salty wit, but can’t bring it to complex, conflicted life: Ngoc is written as so selfless that her self never entirely emerges. What’s left, against its most noble impulses, is a white saviour narrative with no vivid human world to save.

This turn towards insincere condescension – the barbed cynicism that was once Payne’s trademark awkwardly swaddled in a cosy, synthetic blanket – is not, from where I’m standing, a new development in Payne’s work. His most recent films have been startlingly disingenuous in their emotional uplift: The Descendants, a widower-reborn story hailed as a celebration of family and legacy, had a bitter undertaste of misogyny and cultural lip service throughout; his last film, Nebraska, attempts simultaneously to draw sneering comedy from the uncouth lifestyles of midwestern yokels, and to elegiacally mourn the passing of a simpler, purer America.

The tricky, acrid bait-and-switch of Downsizing is not a world away from these films in theme or tone, despite its more extravagantly wacky premise, yet its mild reception thus far is in stark contrast to the universal hosannas and honours that have greeted those previous works. In Trump’s America, does Payne’s particular brand of human satire ring less true than before? Is it no longer enough to obsessively scrutinise the weaknesses of America’s Average Joe without seeking to tell other people’s stories? Or is the film just an odd duck, too eccentric and narratively hobbled to reach its expected fanbase? Either way, the worldview of one of America’s premier auteurs has never seemed quite so, well, downsized.