plantUML file with @startyaml exports to a white page

[Amudtogal]

When opening a file and putting something like:

@startyaml
doe: "a deer, a female deer"
@endyaml

The preview results in a blank page.

Similar things happen for example if using the @startgantt syntax:

@startgantt
[Prototype design] lasts 15 days
[Test prototype] lasts 10 days
-- All example --
[Task 1 (1 day)] lasts 1 day
[T2 (5 days)] lasts 5 days
[T3 (1 week)] lasts 1 week
[T4 (1 week and 4 days)] lasts 1 week and 4 days
[T5 (2 weeks)] lasts 2 weeks
@endgantt

These examples are both taken from the official website (Gantt, YAML).