alter table move partition - row cache lock

DB Version 12.0.1.2

I noticed a strange situation and I`m curios if someone faced a similar situation or have any clue about the reason:

While executing a partition move:
ALTER TABLE t move PARTITION p TABLESPACE t ROW store COMPRESS advanced lob l store AS (COMPRESS medium TABLESPACE tl) UPDATE INDEXES PARALLEL 8;
-> one query slave remain stuck into wait "row cache lock" (p2 = 0, p3 =3)
-> the blocker is actual query coordinator who is idle all this time

Much appreciated,
Laurentiu.

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