The fix for this issue is now available in the latest update of InDesign – that is, InDesign 15.0.2.
Please update your InDesign application to get this fix.
Adobe InDesign team
An error occurred while saving the commentN commented
I've also experienced this issue opening IDML files exported from 15.0.1. Never saw this in earlier versions.
Thank you for reporting the issue to us.
We are currently reviewing it.