Not sure but consider that DDG-150 and 152 of the 052C, although had no reported issues, made complete Aden deployments and are fitted with the same QC-280 GTs. If it was a engineering casualty due to an inherent flaw they would have had 4 years to spot it (DDG-150 was deployed on 18th April 2014. 1st 052C with QC-280s was commissioned at start of 2013).
If it's inherent, at least the 055 hulls before the first one can wait until the its rectified, and this would likely put a delay for QC-280 installation and production.