GTK Theme never applies even if syntax is *seemingly* correct

[nightbright199]

[env]
ENV_VARIABLE = "value"

[GTK]
# Whether to use the dark theme
application_prefer_dark_theme = true

# Cursor theme name
cursor_theme_name = "Vimix-cursors"

# Whether to blink the cursor
cursor_blink = true

# Font name and size
font_name = "Noto Sans 11"

# Icon theme name
icon_theme_name = "Papirus-Dark"

# GTK theme name
theme_name = "Adapta-Nokto-Eta"

[commands]
# The command used to reboot the system
reboot = ["systemctl", "reboot"]

# The command used to shut down the system
poweroff = ["systemctl", "poweroff"]

# The command prefix for X11 sessions to start the X server
x11_prefix = [ "startx", "/usr/bin/env" ]

[appearance]
# The message that initially displays on startup
greeting_msg = "Welcome back!"


[widget.clock]
# strftime format argument
# See https://docs.rs/jiff/0.1.14/jiff/fmt/strtime/index.html#conversion-specifications
format = "%a %H:%M"

# How often to update the text
resolution = "500ms"

# Ask GTK to make the label at least this wide. This helps keeps the parent element layout and width consistent.
# Experiment with different widths, the interpretation of this value is entirely up to GTK.
label_width = 150

Somehow it always becomes the Adwaita darkmode theme

I'm running Arch Linux under Hyper-V under Windows 11 IoT Enterprise stripped down with Tiny11Builder, I am certain the theme packages are installed, I am certain copying the themes from globally installed to locally installed doesn't work.