How to shrink or reuse allocated space of xmltype object relational tables

Oracle Enterprise 19.14.0.0

we are trying to shrink an object relational xmltype table after deleting rows in the main table to reuse the space used by the nested table segments.

There is no error message when issuing "alter table xml_table shrink" or "shrink cascade" or "shrink compact" (after enabling row movement) but the objects won't release allocated space an seemingly won't reuse the space but only get larger. 

Space is only reclaimed when we use a "alter table move" statement but since one cannot use "online" with lobs, this operation is time intensive and because of the size of the table won't and in the maintenance window.