I am experiencing the same problem. I was using Open DCP and now trying the Adobe workflow while checking the results with EasyDCP. The picture seems brighter than when converted with EasyDCP.
The source is ProresHQ, corrected in Rec 709.
I set project settings to none, 16bit and only apply Color conversion effect going from Rec709 to DCDM relative colorimetric and then export to j2c.