refer the following link for more detail
http://www.sharetechnote.com/html/Handbook_LTE_PUCCH_Format.html
While UE in CDRX and eNB receive NACK instead of ACK from UE. After UE sends HARQ feedback UE is not expecting an Retransmission and moved to DRX OFF. But eNB is retranmitting it, How UE handles this?