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Cheshire, 21, who has missed much of the past three years because of repeated concussions, finished sixth.
"I'm really happy with my progression, but I just couldn't put it down tonight," she told BBC Sport.
"It happens and I'm going to take positives from being out there against the best in the world."
Japan's Ayana Onozuka (89.80) took gold in Sierra Nevada ahead of France's Marie Martinod (87.00) and American Devin Logan (84.20).
Cheshire was regarded as a potential medallist at the Sochi Winter Olympics, but a heavy crash in training resulted in a serious concussion that meant she missed the event.
She suffered two further concussions and experienced panic attacks over the next 18 months, only returning to full-time competition this season with under a year to go to the Pyeongchang Games.
"I'm over all of my head injuries," she said. "I'm in a really good place, feeling super-confident and enjoying it more than ever."
Earlier on Saturday, James Woods and Izzy Atkin qualified for their respective slopestyle finals, which will take place on Sunday.
Woods, who finished fifth in Sochi, scored 86.00 to finish fourth in his heat while Atkin, who won GB's first ski slopestyle World Cup gold medal earlier this month qualified in third place.
Although GB's Tyler Harding, Cal Sanderson and Michael Rowlands all missed out, organisers subsequently revised their rules and have added a semi-final on Sunday with the top four to qualify for an extended 16-strong final.

The victims were farming in an area that was declared unsafe because of its close proximity to Mount Sinabung.
The volcano was still spewing ash on Sunday, hampering rescue operations.
More than a dozen people were killed when it erupted in 2014. It also erupted in 2010, after having been dormant for 400 years.
Rescue teams are still scouring the area, looking for more victims who may have been killed or badly burned by the hot gas and ash clouds released in the eruption.
Rescue teams were searching homes and farms in the village of Gamber, which was also evacuated in 2014.
What causes volcanoes?
The 2,460-metre (8,070 foot) tall volcano is among the country's most active.
Indonesia, located on the Pacific Ring of Fire, has more than 120 active volcanoes.
British halfpipe skier Rowan Cheshire crashed in all three of her final runs, but still secured Britain's best-ever World Championship result in the event.
[NEXT_CONCEPT]
Seven people have been killed after a volcano in western Indonesia erupted, blasting clouds of volcanic ash 3km (2 miles) into the sky.