I would like to use Joplin instead of (OneNote, CherryTree, etc.), but Markdown links to the local filesystem, with German Umlaute (äüöÄÜÖß) included, do not work.
Configuration: Joplin 1.0.111 portable Win32 on Window 10.
Link to c:\Mühle <= German word for 'mill'
file:///c:/mühle/ <= Does not work 
or translated to html URL:
file:///c:/m%C3%BChle/ <= Does not work 
Link to c:\Muehle
file:///c:/muehle/ <= Works 
Even more strange
With
<a href="file:///c:/m%C3%BChle/">HTML Link</a>
the content of the preview windows disappears.