Synching music

I'm having music synch issues. I have 600 gb of music so I need to select music to add to devices. Historically no issue. in past few weeks when I burn a CD to my iTunes and try to synch to devices it adds all new music whether selected or not. I have all correct boxes checked. Not synching automatically on start up. I've tried check boxes and the manual synch music page. Still does it. I'm operating itunes (v 12.10.2.3) on a PC (win 10) and the problem occurs on both my Ipod touch and iPhoneX. Both synched fine until recently.