An update (14.0.1) is now available for InDesign CC 2019. The update contains the fix for this issue.
Please install this update via the Creative Cloud application.
Adobe InDesign team
Please let me know if this worked out for you.
Please check the following thread and check if x3/x4 export works again after resetting the color prefs.
Worked out for me perfectly:Nils M. Barner (ACI/ACE) supported this idea ·
Ai & Ps export still working... seems to be an Id issue only!