Cause : Kinetic buffering maximum time exceeded comes when the maximum buffer time (p1255 and p1295 for vector drives with U/f control) has been exceeded without the line supply having returned.

Check the time threshold for Vdc-min controller (kinetic buffering) (p1255, p1295).
See also: p1255 (Vdc_min controller time threshold), p1295 (Vdc_min controller time threshold (U/f))