I posted an answer yesterday, but it didn’t get through moderation while other answers posted at the same did. So I will try again. It is getting bit frustrating however.

You don’t mention which version you are using exactly because CP2019 covers three main versions, and several patch versions. You find the full version number under Help, About Captivate. I double-checked your claim on version 11.5.5.553.

You need to switch to the Expert UI by checking the option ‘Enable custom workspace….’ under Preferences, General settings. Now you get more control over the panels which is impossible with the Newbie UI. The shortcut key SHIFT-CTRL-D works perfectly for the Properties panel in this UI.

Since Captivate version 8 the UI has changed a lot compared with older versions. Are you talking about an older version? If you are using the Newbie UI which is default, you need to click the Properties button top right to open that panel. You cannot create workspaces in this UI neither, nor make panels floating.

If you switch to the Expert UI (Preferences, General Settings, check the option ‘Enable custom workspaces…’) you’ll get some more control. And in that UI the shortcut key you mentioned is still functional, just double-checked.