How to render rail or train tracks in Azure Maps at all zoom levels?

I am trying to render train locations in Azure Maps. To give more context to the train locations I would like to show the train tracks. However, by default, train tracks only appear when very zoomed in. How can I control the zoom levels that rail or train tracks are displayed?

I have manually explored the JavaScript API and discovered that the default map when looking at Australia has two line-type layers related to rail: “Railway” and “Railway outline”. These can be inspected as follows:

map.map.getLayer('Railway')
map.map.getLayer('Railway outline')

Layers are supposed to support minZoom and maxZoom properties as documented here, but setting these has no effect. Setting other properties, such as colour, works.

The map knows where the tracks are, how to render them, and lets you customise the rendering, how can I stop the disappearing when I zoom out?