Issue when using plantuml include in plantuml macro

[programaths]

In a folder, download Some styling as styles.puml.

In the same folder, create the index.adoc file with this content:

title An "inclusive" bug :-D

[plantuml]
--
@startuml
!define DARKRED
!include styles.puml

A -> B

@enduml
--

Expectation

The sequence diagram should be styled (grey background, graphite boxes, white lines)

Observed

There is a plantuml error

Cannot include styles.puml

Remarks

This only happens in asciidocfx, works well with plantuml alone.

Env

Attribute	value
OS Name Microsoft	Windows 10 Pro
Version	10.0.18362 Build 18362
OS Manufacturer	Microsoft Corporation
System Manufacturer	Micro-Star International Co., Ltd.
System Model	MS-7B17
System Type	x64-based PC
Processor	Intel(R) Core(TM) i7-9700K CPU @ 3.60GHz, 3600 Mhz, 8 Core(s), 8 Logical Processor(s)
Asciidoc version	1.7.1
Java	Bundled version