Extension unable to locate designer exe path.

Trying to launch:
qt-ui.openWidgetDesigner
Fails regardless of the : 
qt-core.qtInstallationRoot
Being set to the appropriate path.
Setting 
qt-ui.customWidgetsDesignerExePath
To the location of the designer seems to have no effect on the extension.
Screenshot attached in order:
Path in settings,json -> failure to open
Calling the same path from command line -> opens designer

Note, I tried both:

"/home/lpb/Qt/6.8.2/gcc_64/bin/"
and

"/home/lpb/Qt/6.8.2/gcc_64/bin/designer"To no avail.
At the very least, some instructions should be present on the web page about how to configure this.