When you drew your complex profile fill, where does it sit relative to the 0,0 point of the Complex Profile Editor window?
When I first started using Complex Profiles I had a problem with my Profiles not showing up in my Sections but it was due to the fact they were appearing a couple of storeys above the storey I was cutting a Section through.
Below is a typical cornice scenario, which maybe of some help.
And this is one of the things that is annoying about Complex Profiles. That and curves aren't curves but I suppose you can't have everything
AC versions 3.41 to 25 (UKI Full 5005).
Using AC25 5005 UKI FULL
Mac OSX 10.15.7 (19G2021) Mac Pro-2013 32gbRam AMD FirePro D500 3072 MB graphics