Member pages mix usage of user and member pk's

One-sentence description

The members on the member page of cohort 2017 are not linked to the right profiles.

Current behaviour

When clicking on a member from cohort 2017, get redirected to a different member.

Expected behaviour

When clicking on a member, get redirected to their member page.

Steps to reproduce

1. Go to the member page of cohort 2017.
2. Click on Aniek den Teuling with member id 1559.
3. Observe that you are redirected to Romy Stähli with user id 1559.