Launching images are ignored on Pi 4, but working on Linux PC

[Clyde]

Hi,
I have synchronised RetroPie installations on my Pi 4 and on my PC with Kubuntu 18.04 64 Bit, installed approx. one year ago from the official image (Pi) and Docs/Github (PC). Strangely, for some time now (?), Runcommand shows my custom launching images on my PC as launching art, but screenshots on my Pi instead.

• Both installations are up-to-date.
• I'm scraping the games with Skyscraper, so screenshots are located in [system]/media/screenshots.
• The launching images reside in [system]/images and are named [romname]-launching.png.
• On my PC, the launching images are shown when launching a game. But on my Pi, the screenshots are shown instead.
• The contents of [system] and its subdirectories are identical on both machines, as are their Runcommand scripts according to diff. There are no Runcommand-onstart scripts on both of them.
• When I rename the screenshots directory on the Pi to "screenshots.disabled", it finally shows the launching images. When I rename it back to "screenshots", those will be shown again instead.
• The effect occurs across all systems that I tested, e.g. amiga, arcade, and psx.

Any idea how this can happen?

Thanks for any help
Clyde