Thanks for the clarification.
Recommendation, try to minimize access by revoking unneeded user capabilities from a role 1st. Are ‘edit_posts’, ‘manage_options’ needed for this role?
About a problem, try to temporally revoke the 2nd role from this user. Will admin access blocking work as expected after that? I suppose that you can have other admin menu access restrictions on the 2nd role which can conflict with the 1st one. Check the 2nd role for admin access restrictions. If it has them, show me screenshot. Top of a window is important too, to know what do you select “block selected” or “block not selected”.