Comment (by Samuel Cupp):

I’m also considering the possibility that this could be because the read/writes on two of the functions aren’t right. I based them on the loops (everywhere), but I think the floor_the_lapse and enforce_detgammahat functions actually only need to be read/write (interior). I have to carefully count the number of syncs per iteration to figure this out.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2656/presync-syncing-more-than-old-code