Sparky 7 LightDM problems with some fonts rendering as squares

[bin]

Liking Sparky 7 - thank you.....that is apart from sddm.
Installed lightdm, set as main xsession manager via dpkg-reconfigure etc. Installed gtk-greeter config tool as well.
If I chose Sans as the font for the Greeter, all the text in the login screen shows as squares.
This also happens with Serif, Dejavu Sans Book, and probably others.
Cantarell - which is OpenType is not affected
Free Sans Regular is OK
Monospace Regular shows as squares.
Open Sans Regular is OK
Liberation is OK - after installing.

It sort of seems that it's the core linux fonts that are failing - but I don't know why. They seem OK in applications such as Featherpad. It's just at the login screen they go wrong.

[mls]

Hi all Sparkers,

Today I have installed Sparky7 to check what's new.
I've encountered a problem on my dual core machine that I have managed to solve by now.

After installing XFCE DE from minimal GUI and relogging, the system didn't want to remember that my preferred DE was XFCE and was starting automatically to Openbox. Pretty annoying, given that it was all fine in previous Sparky editions. Then I reinstalled the system without automatic login option and this time XFCE was selected as my preferred desktop, but of course I had to enter password at each computer start (better than switching from Openbox).
I found out that instead of lightdm the system uses sddm. Of course I could install lightdm but wouldn't that trigger other problems? So I edited etc/sddm.conf adding xfce in lieu of openbox and that worked for the "automatic login wersion". For the "non automatic login version" I had to create directory and file /etc/sddm.conf.d/autologin.conf as explained here:
https://suay.site/?p=3350

It's taken me a while to figure it out, something that was no issue in previous distros.
Sddm simply doesn't recognize my last DM as my default DM, at least on my machine.
Hope that this information will be helpful.

cheers