Works here, with some annoyances- e.g. pcmanfm cannot set the desktop wallpaper.
Contents of ~/.config/pcmanfm-qt/lxqt/settings.conf
[Behavior]
ConfirmDelete=true
SingleClick=false
UseTrash=true
[Desktop]
BgColor=#00557f
FgColor=#ffffff
Font="Verdana,10,-1,5,50,0,0,0,0,0"
ShadowColor=#000000
ShowHidden=false
SortColumn=name
SortOrder=descending
Wallpaper=/home/panfren/wallpapers/Oia-Santorini-1050x1680.jpg
WallpaperMode=fit
[FolderView]
BigIconSize=36
Mode=icon
ShowHidden=false
SidePaneIconSize=24
SmallIconSize=24
SortColumn=name
SortOrder=descending
ThumbnailIconSize=128
[System]
Archiver=file-roller
FallbackIconThemeName=elementary
SIUnit=false
SuCommand=gksu %s
Terminal=konsole
[Thumbnail]
MaxThumbnailFileSize=4096
ShowThumbnails=true
ThumbnailLocalFilesOnly=true
[Volume]
AutoRun=true
MountOnStartup=true
MountRemovable=true
[Window]
AlwaysShowTabs=false
Height=480
ShowTabClose=true
SplitterPos=150
Width=640
But still, the background remains blank.