[jgrahamc]

Well, it could easily be that they hit the CoCom limit on the GPS units they were using: http://blog.jgc.org/2010/11/gaga-1-cocom-limit-for-gps.html

Perhaps the GPS devices were disabled by speed, or altitude, and didn't have time to reset while at apogee to get the reading.

[JabavuAdams]

Yes, this. There's an ongoing discussion on arocket regarding these issues. It's a problem for many amateur teams.

[nknight]

I'm surprised they didn't specifically seek out a receiver that implemented the rule correctly. Since it's an "and", not an "or", a proper receiver should have kicked back in by the time it reached apogee.