Cannot digitally sign document on ubuntu 17.20, LO 6.0.3.2

[whitehat]

I’m attempting to digitally sign a document on ubuntu 17.10, Libreoffice 6.0.3.2
I bring up the document in writer. I select File->Digital Signatures->Digital Signatures.
I am presented with the “Digital Signatures” dialog box.
I select the button “Sign Document”.
Another dialog box is presented, with the title “Select Certificate”.
I see no Certificates listed in the dialog box.

Kleopatra displays a number of certificates.

When I perform the same procedure on Windows Pro 7 using Libreoffice 6.0.3.2
the Select Certificate dialog box is populated with various certificates. I can
select the certificate from the dialog box and sign the document.

Any ideas why “Select Certificate” dialog box contains no certificates?
Thank you.

[Lurch]

Same issue in JunoBeta. Tried with tutorials, didn’t work, except by creating a rudimentary certificate in terminal, described here
Tried this procedure, and this procedure to no avail, even havin LO pointing at folder.