Yes, this is known, sddm theme is not yet ready.

what theme does lxqt use?  Apparently not 02-fedora ?  (that one should 'just work', as it only references /usr/share/backgrounds/default.png )

if not 02-fedora, can you re-assign this to whatever provides it?

ping, comment #2 question still remains unanswered

I did not configure any special theme here, so should be sddm default. Have to investigate what i have to change.

OK, so it appears that sddm's behavior of finding fallback themes has changed recently (maybe in 0.14 that I failed to notice).

/etc/sddm.conf contains:
[Theme]
Current=01-fedora-breeze

the fallback behavior *used* to be that if 01-fedora-breeze was not present, it would choose the next one alphabetically, which would end up being 02-fedora

That is no longer the case.  

sddm now appears to use some internalized fallback (maui?):
* employs userlists (not sure if it gracefully can handle large numbers of users like breeze can)
* does not use fedora wallpaper

Options include:
* spins (like lxqt) can force/customize sddm.conf via kickstart to use a theme of their choice (like 01-fedora)
* I can try find some better global fix for fallback theme

Sorry, when I said 01-fedora in comment #5, I meant 02-fedora

Well, who feels responsible for a fix or at least to work around this issue?

> * spins (like lxqt) can force/customize sddm.conf via kickstart to use a theme of their choice (like 01-fedora)
+1 IMHO, this option can fix the live image at least.

Reassigning for now, has to be fixed in sddm in general, not only LXQt.

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