Brake Master Cylinder problems of the 2007 Nissan Versa

Reporting an issue with the 2007 Nissan Versa intermittent brake failure. When driving on dry roads and braking hard, the brake pedal would go to the floor, then recover itself and have adequate pressure within about a minute. Car has been regularly serviced since purchase, including annual brake service. This issue has occurred twice in the car's lifetime - the first time, the driver was able to maneuver the car out of traffic without issue. Full brake system was checked out with no issues found in master cylinder or other hydraulics and unable to repeat issue. After 1. 5 years, the second time the issue occurred, the driver was in stop & go rush hour traffic on dry roads and when hitting the brakes, the brake failure caused a collision with another vehicle with airbag deployment. Full brake system check by multiple shops showed no issue with brake hydraulics, and again was unable to repeat the issue. Brake fluid had been recently exchanged. Owner has requested event data recorder info pull from Nissan USA to determine that brake pedal was applied and car did not slow down - Nissan USA stating $600 fee plus 1 month lead time until such data can be pulled from the vehicle. Nissan tech has confirmed that such an issue has been seen in some vehicles, but cannot confirm cause, only that replacement of a working master cylinder has fixed the problem, which goes against reason of replacing something that is functioning under standard test conditions.