STEP 1.  Subjects must be enabled.  Go to the Subjects page and ensure subjects have a tick in the Enabled column ie they are available to select

STEP 2.  Subjects must be in a Preference Group.  Go to the Preference Group page and on the second tab click Preference Group Subjects and move any subject that should be available to the Selected column and click Save

STEP 3.  Subjects can be gender specific, if a student has no gender recorded or is a male and the subject gender is set to female, the subject will not display in the student portal

STEP 4.  Check you are opening the correct Student Portal.  Go to the Student page and click "Open Student Portal" located on the far right hand side of the page in the same row as the student