Thank you for your patience all this while.
This issue is now fixed in the latest update (Id 14.0.1) of InDesign CC.
If you are unable to see the update notification yet, open the menu (three dots) from the top-right of Creative Cloud desktop application and click on ‘Check For App Updates’.
Once the update button is shown against InDesign CC, click on the button to update your InDesign to Id 14.0.1 for the fix of the issue.
Do let us know in the comments, if you face any problem with the new update.
List of fixed issues can be found at: helpx.adobe.com/indesign/kb/fixed-issues.html
InDesign TeamNicole Wünsch commented
me too; all functions concerning fonts take ages while ID is frozen; had to switch to ID2018 again