When attempting to check out an item associated with an active booking (either via normal checkout or using "Transform to checkout"), Koha may throw a Koha::Exceptions::Booking::Clash and return a 500 error even when the booking dates and item assignment are valid. This appears to occur during the booking store() logic where both item-level and biblio-level check_booking() validations are executed. In some cases the biblio-level booking check incorrectly reports no available bookable items even though the booked item itself is valid, causing checkout to fail. The expected behavior is that a booking transitioning to checkout should complete successfully without triggering a clash when the assigned item and booking dates are valid.