Dependencies confusion

My project includes a library of my own (SimpleNode) that includes various other libraries. For reasons, I need the Head of ESP Async WebServer, rather than the official version (1.2.3).
When my library lists ‘any’ version of the WebServer as a dependency, everything compiles fine, but when I list the specific version, I get header problems, even though the header is present. I believe the issue is that the library path is not being included in the compiler invocation, but I cannot fathom why.
It’s surely an easy fix, but I’m out of ideas.

Working case:
SimpleNode/library.json:

...
"dependencies":
  {
    "adafruit/Adafruit NeoPixel": "*",
    "adafruit/Adafruit MQTT Library": "*",
    "arduino-libraries/NTPClient": "*",
    "me-no-dev/ESP Async WebServer": "*"
  },

Build highlights:

Library Manager: Installing me-no-dev/ESP Async WebServer @ *
Unpacking [####################################] 100%
Library Manager: ESP Async WebServer@1.2.3 has been installed!
Library Manager: Resolving dependencies...
Library Manager: Installing AsyncTCP
Library Manager: Warning! More than one package has been found by AsyncTCP requirements:
Library Manager: - me-no-dev/AsyncTCP@1.1.1
Library Manager: - zeed/AsyncTCP@1.1.1
Library Manager: - kubafilinger/AsyncTCP@1.1.1
Library Manager: Please specify detailed REQUIREMENTS using package owner and version (shown above) to avoid name conflicts
Unpacking [####################################] 100%
Library Manager: AsyncTCP@1.1.1 has been installed!

...
Scanning dependencies...
Dependency Graph
|-- SimpleNode

....
Successfully created esp32s3 image.

Broken case
SimpleNode/library.json:

...
"me-no-dev/ESP Async WebServer": "https://github.com/me-no-dev/ESPAsyncWebServer.git"

Build highlights:

Library Manager: Installing git+https://github.com/me-no-dev/ESPAsyncWebServer.git
git version 2.34.1
Cloning into '/home/edd/.platformio/.cache/tmp/pkg-installing-ua45j58l'...
remote: Enumerating objects: 61, done.
remote: Counting objects: 100% (61/61), done.
remote: Compressing objects: 100% (53/53), done.
remote: Total 61 (delta 3), reused 38 (delta 1), pack-reused 0
Receiving objects: 100% (61/61), 270.18 KiB | 2.70 MiB/s, done.
Resolving deltas: 100% (3/3), done.
Library Manager: ESP Async WebServer@1.2.3+sha.f71e3d4 has been installed!
Library Manager: Resolving dependencies...
Library Manager: Installing me-no-dev/AsyncTCP @ ^1.1.1
Unpacking  [####################################]  100%
Library Manager: AsyncTCP@1.1.1 has been installed!

...
Scanning dependencies...
Dependency Graph
|-- SimpleNode

....
In file included from /home/edd/Arduino/libraries/SimpleNode/SimpleNode.h:15,
                 from include/common.h:4,
                 from src/control.cpp:3:
/home/edd/Arduino/libraries/SimpleNode/include/webserver.h:3:10: fatal error: ESPAsyncWebServer.h: No such file or directory