Checkpoint state invalid for both Zarr and OCDBT formats

[plra]

I'm using jax 0.4.34, flax 0.9.0 and orbax 0.7.0. Until recently I was using orbax 0.4.1. Certain checkpoints created with v0.4.1 have the following directory structure:

path/to/old_ckpt/
  0/
    commit_success.txt
    default/
      _sharding
      checkpoint
      commit_success.txt
      d/
        <hash>
        ...
      manifest.ocdbt
      <myparam>/
        kernel/
          d/
            <hash>
          manifest.ocdbt
      ...

For at least some of these checkpoints, when I try to restore with a PyTreeCheckpointHandler I get

ValueError: NOT_FOUND: Error opening "cast" driver: Error opening "zarr" driver:
Metadata at "<myparam>/kernel/scale/.zarray" in OCDBT database at
gs://<checkpoints>/<model>/<run>/<step>/default/ does not exist

Downgrading orbax back to 0.4.1 results in the same error. Did I corrupt my checkpoint state somehow? How can I rehabilitate these checkpoints?

For reference, my modern checkpoint dirs look like this:

path/to/new_ckpt/
  0/
    _CHECKPOINT_METADATA
    commit_success.txt
    default/
      _METADATA
      _sharding
      commit_success.txt
      d/
        <hash>
      manifest.ocdbt
      ocdbt.process_0/
        d/
          <hash>
          ...
        manifest.ocdbt

and I can load them just fine.