[Elle Bee]

the CVR tape only records the last 30 minutes

Just a guess here ... something was recorded in the last 30 minutes they didn't want for prosperity so they flew on for enough time to record over the last 30 minutes

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[Regulator]

Actually digital CVR's record 4 tracks for 2 hours, not all airplanes have them of course...or so I've read.

But your theory still might hold water, just have to look further back.

I still think they were snoozing.