make sure you have apple menu >system preferences >displays >colour and selecting the profile you want to use
and
AE view simulate output
then before you open AE,
customize the interpretation rules file. When you import a footage item, After Effects looks for a match in the interpretation rules file, and then determines interpretation settings for the footage item. You can override these settings after importing, using the Interpret Footage dialog box.
In most cases, the name of the interpretation rules file is interpretation rules.txt; however, some updates to After Effects install a new interpretation rules file with a name that indicates the updated version number, and the updated application uses this new file. If you have made changes to the old interpretation rules file, you may need to apply those changes to the new file, too.
Quit After Effects.
As a precaution, make a backup copy of the interpretation rules file. By default, this file is in the same location as the After Effects application.
Open the interpretation rules file in a text editor.
Modify the settings according to the instructions in the file.
Note: You must supply a four-character file-type code for each footage type or codec. If you don’t know the code for a file or codec in a project, press Alt (Windows) or Option (Mac OS) as you select the file in the Project panel. The file-type code and codec code (if the file is compressed) appear in the last line of the file description at the top of the Project panel.
Save interpretation rules.txt in the same folder as the After Effects application.
why AE grey is..
Non-RGB footage items (e.g., CMYK, Y’CbCr, and camera raw images) cannot be assigned an input profile. Their native color space is displayed in the Interpret Footage dialog box. Conversion of non-RGB color values to RGB color values is handled automatically for each format.