Failure to show in an external display a spreadsheet embedded in Impress

I create an Impress file in which I embed a Calc spreadsheet that had been created previously.
I connect an external display to the computer via an HDMI port.
The presenter console is enabled.
I wish to manipulate the spreadsheet as part of a slide show.
As far as I can see, changing the spreadsheet is not possible when in slide show view, so when I reach the slide with the embedded spreadsheet I exit slide show view to Normal view and double-click the spreadsheet.
I can now make the changes that I wish to show the audience.
HOWEVER, while the spreadsheet is visible on my own computer, it is NOT displayed on the external screen, which is blank.
If I leave the embedded spreadsheet and return to slide show view, the external screen displays the slide correctly.
My question: can anyone reproduce this behavior? Is it a bug in LibreOffice? A limitiation due to the operating system (Ubuntu 16.04)? Some other issue?