Fix for this issue is now available in the latest update of InDesign 2020.
In the Creative Cloud Desktop application, click on the Updates section on the left. You should be able to see the Update available for InDesign. Please update your InDesign application to this version to try out the fix.
Let us know in the comments section if you face any problem with the updation process.
Adobe InDesign Team
An error occurred while saving the commentHans Christian commented
InDesign CC 14.02 and Mojave 10.14.5 after a clean install: still the same problem. After 8 months, really!!!