OIC3 Error setting up storage for export

Summary:

I'm getting this strange error when setting up a storage bucket in OIC Gen 3 for export:

ERROR An error occurred while saving storage changes
{ "servlet":"jersey", "message":"insufficient content written", "url":"/ic/api/common/v1/storages", "status":"500" }

The same bucket with the same Swift URL and credentials worked fine earlier in Gen 2

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