The root cause is a change to the domain model, made in preparation for future ERP and pricing work. We introduced overly strict input validation for category values. The validation rules did not account for special characters present in UK item-location data, causing valid records to be rejected and downstream processing to be disrupted.
Input validation has been relaxed, and automated tests that verify validation against these specific UK item-location values have been added.
We apologize for this incident and its impact.