Barclays BACS file pulls the employee name from the Basic Details tab in their employee record, rather than the name on the Bank Account tab.
This therefore includes the employees full name (including middle name) so the name cuts off on the BACS file.
I totally agree that this is ridiculous that in the employee details we add a specific payee name, yet the bacs file completely ignores this input and takes the employee name, which due to various reasons could be different!