Are you using ACES in the project “Color Management” panel? Or, AcesTransform?
If you manage you project in AcesTransform you can try the following: use a ColorspaceTransform to go from IPP2 to Arri Wide Gamut and use the ARRI IDT. That “might” help.
Note that the best way I foung to apply the aces_fixHighlight.dctl file is to sandwhich it between the IDT and ACES Ap-0. You can then go from Ap-0 to ACEScct for grading.
Cheers