The fix for this issue is now available in the latest update (14.0.2) of InDesign 2019.
If you are unable to see the update notification, 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, click on the button to update to Id 14.0.2.
If you face any problems with the new update, do let us know in the comments.
The list of fixed issues can be found at: helpx.adobe.com/indesign/kb/fixed-issues.html
Adobe InDesign team
An error occurred while saving the commentPhil commented
Same issue as Rich Mooney. Good point by Luke. I think I'll get used to the Properties panel, but the sub-panels MUST stay expanded. Glad to hear you've started implementing it. Will it be part of the next update? (I'm on CC 2019 14.0.1) Thanks!