More details have now become available as the Government passes COVID-19 Response (Urgent Management Measures) Amendment Act.
These would be considered non-essential services, and are now deferred until the lockdown period is over or the restrictions go down to Level 3.
These maintenance issues are likely to be considered non-essential services and are expected to be deferred until the lockdown period is over or the restrictions go down to Level 3.
Depending on the nature of the problem, this can be considered essential or non-essential. If the maintenance issue is related to power, water, gas, waste (the essential services), then the landlord can contact an essential services company to perform the repair.