In whatever Black Mirror universe where Radiohead are happy and Coldplay are interesting, Alt-J must make some kind of sense. In this one, the only explanation is they are wilfully baffling.

Think folksy chants as performed by Kraftwerk, bits of binary code in place of lyrics, synth crescendos crashing to a halt to leave Joe Newman's nasally vocals standing a cappella. Occasionally there's a moment vaguely resembling a chorus.

Planted in position amid a shower of lights, and often disappearing under their brilliance, the three lads from Leeds opened with the subdued, meditative 3WW from this year's Relaxer. They turned quickly to 2012's breakthrough, Mercury Prize-winning debut An Awesome Wave – from which they played just about everything, including interludes about barking dogs.

Tessellate and Dissolve Me had magical moments, but a lack of impulse control gave them a stop-start quality which prevented them from being truly transcendental. They rectified this with fan-pleaser Matilda, pausing the strobe show and letting the crowd see the band.

Alt-J's maximalist tendencies served them well on Hunger of the Pine, the Miley Cyrus-sampling lead single from the UK chart-topping This is All Yours (2014).

The stage flashed as if at red alert, and midway through the band was lost completely in a slow-motion supernova. Better still in the baby-bathwater-kitchen sink brigade was The Gospel of John Hurt: references to biblical figures, Tetris and chest-bursting aliens describe the lyrics, and musically it was the night's most epic and emphatic moment.

Of the new work, In Cold Blood is catchy, Deadcrush is both funky and more forgettable, while Pleader takes an orchestra on a picnic over rolling hills to the refrain of "How green was my valley" before turning ominous.

The show ended with the blues-driven Left Hand Free and biggest hit Breezeblocks, which were delivered with enough panache to lift them above the perfunctory.

Whatever faults Alt-J may have – a lack of musical focus, vocals that are more unintelligible than not, a tendency to be self-serious – they were never boring and never bad. But as they slipped back to wherever they make sense, it was hard to escape the feeling something is stopping them from being great.