Derive color from background issue

[MalditoBarbudo]

Hi.
I have elegance-colors setted as shell theme and color derived from background setting.
When I load a "official" GNOME background (backgrounds tab in GNOME background settings) color changes without problem, but when I load a "custom" background (from Images tab in GNOME background settings) color is not changing: it takes the last "custom" color set in elegance-colors config).
I've tried with *.png and *.jpg images but both doesn't work.
It was working fine last month or so, so I don't know if this is due to elegance-colors update or I messed up my config in some way (only change I've made is change the background)