Help investigating: Wandb offline experiments sometimes not synced - Silently dead Syncer?

Severity of the issue:
Medium: Significantly affects my productivity but can find a workaround.

I store my wandb offline and then after tuning finished want to upload them.
Very roughly:

results = tuner.fit()  # with a Wandb Callback
for result in results:
    # upload Path(result.path) / "wandb"

However, this often, but not always fails (~2 / 3 of times). The dict were the wandb data should be (result.path + "/wandb") does not exist in these cases.
The files in /tmp/.../wandb are there as reported by the WandbLogger output
I thought the sync is not yet done and added some time.sleep which also did not help and even manually checking the dir after some time: it is still empty.

My assumption is that the syncinc process is dead without raising visible errors.

Do you have any ideas what could cause the issue, and how I could debug it?

Sidenote: I see this issue in a test of mine which just runs for two iterations. It appears setting it to longer test does sync the files properly more reliably. So I think there might be a bug involving short tune runs. Other non-wandb files seems to be synced correctly.