Oracle 12c database parallel coordinator wait

I need some assistance with an oracle sql that performs well in oracle 11.2.0.4 RAC but I have a significant wait on parallel coordinator when run on 12.1.0.2. RAC

UPDATE /*+ PARALLEL(a) */

mrsty_pre a

SET cvf =

(  SELECT NVL (cvf, 0) - BITAND (NVL (cvf, 0), c.code) + c.code

FROM mrd_content_view_members c, mrd_classes b

WHERE a.cui = b.cui

AND c.code = 256

AND meta_ui = b.aui

AND c.expiration_date IS NULL

AND b.expiration_date IS NULL

GROUP BY c.code)

WHERE a.cui IN (SELECT cui

FROM mrd_content_view_members c, mrd_classes b

WHERE c