writer Page Size and Page Columns drop-downs unresponsive

Hello
I’ve just re-installed my machine to Manjaro and installed LibreOffice as part of the build

I’ve realised that all pages are defaulted to American Letter size (despite my having chosen GB locale during the install)
so I have to change the page size each time before I print (otherwise my printer won’t print)

I have set LibreOffice view to the tabbed interface but find that the [Page Size] and [Page Columns] drop-downs don’t work
I can use the sidebar setting, or the [Page settings] to the right on the “Layout” ribbon.

My questions are why these drop-downs don’t work, and if there’s a fix?

As a side-note, I have created A4 templates, set as default

Thanks

Seems to be #tdf130641 (see Comment #5 in the bug report, which deals with Linux - same on my openSUSE 15.1 using LibreOffice 6.4.3.2) and this seems to be a KDE thing on Linux - using GTK3 interface with Linux works