Are any new fonts used? Is it the same document that worked before?
Can you send the first 50% of the pages to CTP and if that works try the other 50% of pages - whichever side it fails on is where the issue is. You can keep dividing and conquering the pages to track down the pages.
Any new images introduced/fonts/styles? Are you sure it's the trapping? What have you tried to test this?
Could you try using File>Export and choose IDML - open that up in InDesign - resave as an indesign document using a new file name.
Does the issue persist?
You could try:
Try resetting your preferences: The easiest way to reset everything is to delete the InDesign preferences: as soon as InDesign starts to boot hold down Shift, Alt, Ctrl (and Apple/Cmd if working on a Macintosh). A dialog will appear asking to delete the InDesign Preferences, select 'Yes' on this dialog. Further info and instructions here if needed: https://helpx.adobe.com/in/indesign/kb/indesign-preferences-support-file-locations.html