Can't install Kokoro model or backend

[FoolRunning]

LocalAI version:
v4.2.6 (6a48157)

Environment, CPU architecture, OS, and Version:

Describe the bug
Attempting to install the Kokoro model or backend results in the following error:
no backend found with name "kokoro"

To Reproduce
Attempt to install either the Kokoro AI model or the Kokoro backend through the LocalAI UI.

Expected behavior
The Kokoro backend would be found and installed.

Logs

Additional context

[localai-bot]

The kokoro backend is present in the gallery index (backend/index.yaml, including the per-arch variants). 'No backend found with name kokoro' on v4.2.6 usually means a stale local backend gallery index - please refresh the backend gallery (or update to the latest image) and retry. If it persists, attach the startup DEBUG logs.

[FoolRunning]

Now that I know where the gallery comes from, after looking at it, I'm guessing the problem is that I'm using Vulkan and there doesn't seem to be any variant specified for that (and also no default).

Trying other backends that have a similar problem (no Vulkan and no default), like coqui, leads to the same error message. That seems to be the common thread.