Enabling this option in Dolphin - Configure Dolphin - General - Previews, disable thumbnails generating for Sony ARW raw files.
It is irrelevant what packages, plugins (combinations) are installed for thumbnails.
Arch - Latest KDE Plasma

Works well for Nikon NEF raw files even with this option activated.

Took me one whole week and all possible tweaks and config to realize this.
If anyone can explain it would be very nice. Thanks. Because it makes it almost impossible to play with search keywords on Google and find answer.

Hm, this could be a thumbnailer problem, not Dolphin per se, as it also just uses an additional application, kdegraphics-thumbnailer

Please also check that the Preview is not set too low (Settings -> General -> Preview). RAW files can get quite big and there is a limit in size you can change there.

If this fails, please report this to the bug tracker at https://bugs.kde.org/enter_bug.cgi?prod ... nt=general

Sony is one of those that uses arw as raw. True, you can not disable that specific format to show as a thumbnail. Showing, yes. Disabling the thumbnails for those, no.

- There are no size limits. Played with that too without better results.

- My SSD disk died and I had to install Arch again and I can confirm this problem. It is something in conjunction with kdegraphics-thumbnailers.

- Dolphin tries and succeeds to show just few thumbnails of, we say, hundred of images. And stops. Often are those thumbnails everywhere randomly, not in some particular order.