Answer
This is by design, not a bug — Customers - CRM is intended as a read-only overview page in Aurena, for viewing rather than directly editing customer data; this same read-only behavior has been confirmed even on IFS's own reference environment logged in as the application owner. To actually edit a customer's data, drill into the specific record's own detail screen rather than trying to edit inline from this overview page. If this behavior genuinely doesn't meet a real business need compared to IEE's equivalent screen, raising a case with Global Support is the right path to request it be reconsidered.