i3WM thunar heic/heif thumbnails

yes, tumbler is installed. reinstalled gdk-pixbuf2 and rebooted, but no effect.
I followed the instructions on the libheif github page.
No success. Nemo is capable of showing thumbails for the heic and heif files, after I’ve increased the size limit for which nemo is showing previews.

In the tumbler.rc file the PixbufThumbnailer is configured. And libheif states that they provide a gdk-pixbuf loader.

Any idea for getting thunar heif capable?

ARW files have no thumbnails in thunar either. If i change the priorities in the tumbler.rc file so that a dedicated rawthumbnailer has a higher priority as the pixbuf thumbnailer, than ARW files do have thumbnails.

Maybe this whole thing has to do with pixbuf not working correctly? But " gdk-pixbuf-query-loaders" outputs information libopenraw_pixbuf.so and libpixbufloader-heif.so.

In the ~/.cache/thumbnails folder are thumbnails for jpeg files but not for heif files. So I assume the thumbnails are never generated.