organic chemistry - Order of halide nucleophilicity in DMF

The order of nucleophilicity for halide family in DMF is: $\ce{Cl- > Br- > I-}$. I understand the reason for this must be that DMF, being a polar aprotic solvent, is unable to solvate the halide ions.

I was told by my teacher that this is true only for DMF and DMSO, while in other aprotic polar solvents, the order is as usual: $\ce{F- < Cl- < Br- < I-}$.

I'd like to know what is special about DMF and DMSO (and which is not possessed by other aprotic solvents like acetone) that leads to this order.

I have verified the order in DMF from March's 7th edition (page 427). The book mentions the usual order ($\ce{Cl- < Br- < I-}$) for acetone (another aprotic polar solvent).