remapJar fails for common module: java.lang.NullPointerException: tinyRemapper

[Fuzss]

I have a multi-loader setup with multiple common modules (to allow for shared code between some, but not all mod loader subprojects). The subprojects are related as follows:

- Common
    |- Common-ForgeApi
        |- Fabric
        |- NeoForge
    |- Common-NeoForge
        |- Fabric
        |- Forge

When building Common-ForgeApi and Common-NeoForgeApi for publishing to Maven the task fails:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':1.20.6:Common-NeoForgeApi:remapJar'.
> A failure occurred while executing net.fabricmc.loom.task.RemapJarTask$RemapAction
   > Failed to remap, java.lang.NullPointerException: tinyRemapper

However, building any of the other subprojects including Common does not run into any issue.
All three common subprojects set the targetNamespace to named, since I need the builds to be usable independently of Loom, e.g. with VanillaGradle.
Leaving the targetNamespace as intermediary does not run into the remapping issue, but as mentioned I need to publish my common builds as named.

This has not been an issue on Minecraft 1.20.4 when I was still using ArchLoom 1.5. The Gradle scripts have not been changed in any way during the update.

The repository containing all my code can be found here: https://github.com/Fuzss/forgeconfigapiport/tree/main/1.20.6
The issue can be reproduced by running either Common-NeoForgeApi:build or Common-ForgeApi:build.