Something seems strange here, adding in the motion parameters and their first derivatives into the aCompCor model made the correlation with FD stronger, which is strange since FD is just a linear combination of the motion parameters. Similarly, adding in the 6 motion parameters induces a higher correlation with FD than the base model.
I wonder if there’s any additional filtering steps and when they might be? I know that bandpassing just the BOLD data prior to regression actually induces artifacts and does a poor job accounting for the covariates.