All went well for the first three hits before she crashed out a second time, attempting a backside 540.
Sinclair upped her score to 48.25 but by the end of the heat her 11th place was not enough to progress any further.
"This was definitely not the result we were hoping for at all and definitely not the result Bex is capable of," commented her coach Tom Willmott. "We're really gutted, she's really disappointed."
The day had brought warm temperatures, making for soft and slow snow conditions in the halfpipe and fewer than half the field in heat one had been able to land clean runs.
"The halfpipe was in absolutely fantastic condition, the snow was soft but we ride these kinds of conditions all the time and by no means was the condition of the pipe a factor what so ever," Willmott said.
"It's been described as running a hundred metre sprint along a tight rope; unfortunately today Bex fell off."
The New Zealand Olympic Team will see Jossi and Beau-James Wells in competition on the freeski slopestyle course tomorrow and Katharine Eustace in day one of women's skeleton.