I'm struggling here with this. I've made myself a 4k overlay and put it in a folder.
clean install of coverart, select default profile and select icons under media info, all works ok with the included icons, 720, 1080 and uhd.
if i select the folder the custom .pngs are in and select custom instead of icons, 4k films have no overlay, seems to not see the hdtype_uhd.png in the folder.
but heres the weird thing, If i rename hdtype_uhd.png to hdtype_720.png it shows up on the covers for 720 films. so the .png must be right.
just doesn't seem to work for the 4k films.