Hi, Eloisa,
a few questions: which thorn are you using to fill in the position_* scalars? Is it doing anything at recovery? Are you using the parameter Carpet::regrid_during_recovery?
I'm using Whisky, and the carpetregrid2::positions are computed by "Whisky_MoveCarpetGrids" thorn.
I'm using the parameter, Carpet::regrid_during_recovery = "no".
Kentaro