We're getting a "metafields.key must be unique within this namespace on this resource" error attempting to update metafields on a product via the REST API.
The key values are indeed unique; however, they share a common prefix that contains an "&" character. For example:
Is this perhaps causing the key text after the "&" (the unique part) to be ignored?
Are there special characters which should not appear in metafield keys? There is no mention of such restrictions that I have found yet in the Metafields API documentation...
Or are there perhaps key length limitations that are truncating the keys before the unique part is reached?