On macOS I can't open image files with german names that contain umlauts on cloud drives

[visualnotes]

Under macOS, I cannot open image files with German names containing umlauts on cloud drives.

If I have files with German names containing umlauts, such as "Käsekuchen.jpg" on a cloud storage like pCloud or Google Drive, I cannot open them with XnViewMP. The same goes for files with umlauts on FTP drives.
XnViewMP is not even able to create previews for files with such names.
However, as soon as I change the name from "Käsekuchen.jpg" to "Kaesekuchen.jpg", the image is displayed correctly.

It took me a while to figure out that this problem is not caused by the cloud storage, but by XnViewMP itself. The image viewer app "Lyn", for example, can open images with umlauts in the name on cloud drives without any problems. Also the preview app that comes with macOS can handle image files with German umlauts on cloud drives.

Since I want to use XnViewMP instead of Lyn to work with image files, it is extremely annoying that I have to rename all files with umlauts in their names to display them correctly.

I'm using the latest versions of macOS (currently Sonoma 14.0) and XnViewMP (v. 1.6.1).

[xnview]

i've tried on sonoma, and a file "Käsekuchen.jpg" on GoogleDrive is opened correctly...