Hi JBL Admin.
I had exactly the same issue as you. We are on Moodle 3.5 - I had checked everything and have worked with our provider but I had still not been able to resolve this issue.
I searched through the forums and found the following post: https://moodle.org/mod/forum/discuss.php?d=399140#p1610478 see the final post.
I ended up removing the following capability for role based on the archetype manager role: the capability is: moodle/course:update
I have tested the role and the ability to edit front page settings is now removed. I checked that the role can still edit course - which is what we require.
Kind regards. Paul.