Hmm that is interesting. I would be curious if you set the colorspace settings to their default, if the colors would show up as what you expect to see. If that is the case, it would narrow it down to the ACES AP0 you have set it to. I’m sorry to say I am not familiar with working in that colorspace.
It is possible to disable the tone mapper in a post process volume, as well as in the Preview Scene Settings of the Material Editor. You could try setting Tone Curve Amount to 0 and apply your colorspace alterations in a Post tool such as Nuke, or Davinci.