PlantUML not finding custom stylesheets

Question

I attempted to replicate the directory structure in this tutorial by jerieljan. Unfortunately I seem to be getting the default PlantUML stylings. I have included the expected results vs. the actual results in screenshots below. I am using the Visual Studio Code extension by jebbs with preview. While the style sheets are too long to include here they can be found in the aforementioned linked tutorial. The diagram file is as follows:

# Sequence Diagram Example
@startuml
    'General Defaults
    !define BASEPATH ..
    !include BASEPATH/globals/stylesheet.iuml

    'Actor Definitions

    autonumber 1 "0:"
    title Sequence Diagram

    A -> B: Perform Action
    B --> A: (Response)

@enduml

The directory structure is the same as in the tutorial and is as follows:

$ tree
.
├── globals
│   ├── style-presets.iuml
│   └── stylesheet.iuml
└── diagrams
    ├── example-sequence.puml
    ├── etc...

Expected Diagram

Actual Diagram