single file editor hangs with spinner when attempting to edit a file in a subdirectory of a project

Gitlab 17.1.1ee / running on RHEL7 (installed via yum)

After upgrading our open source project's gitlab instance (gitlab.jalview.org), I discovered that the 'single file' editor isn't working for some files. Everything seems fine when opening an editor for a file in the top level of a repository, but when trying to edit a file in a subdirectory, the editor hangs:

https://gitlab.jalview.org/website/jalview-site/-/edit/main/archetypes/default.md?ref_type=heads

The dev console reports a 404 for: https://gitlab.jalview.org/api/v4/projects/3/repository/files/archetypes%2Fdefault.md/raw?ref=main

All healthchecks seem fine, gitops, builds, etc seem to work too - and single file editing works fine on a top level file: https://gitlab.jalview.org/website/jalview-site/-/edit/main/.gitlab-ci.yml?ref_type=heads