Impossible to book an appointment despite option being available

<img style="margin:0 1em 1em 0;" align="left" alt="The logged-in section of Heilsuvera will be discontinued and its functions transferred to My Pages on Ísland.is." src="https://c.arvakur.is/frimg/1/67/43/1674340A.jpg"/> At most primary healthcare centers, it is not possible to book an available appointment with a general practitioner through Heilsuvera, despite the option being available to users.