Fix for this issue is now available in the latest update of InDesign 2020 – that is, InDesign 15.0.1
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 commentC. Roger Jeffries III, EdM, CCIM commented
This exact thing is happening to me. It worked fine one day and then I think the last update screwed it up. I also notice the numbers only disappear when you use commas to separate the thousands. Please fix ASAP. There is money on the table with proposals I submit to win business. I need this fixed yesterday just like everyone else.