If you have a file named, for example:
6A1b2 Mr. Lorem's statements conflicts with blah blah blah.md
and create a wikilink to that file, then try following it, Emacs will open a new file named
6A1b2 Mr. Lorem's statements conflicts with blah blah blah
meaning that obsidian.el has not been able to find the file.
Notice there is no .md extension. I don't really know why this happens. So for a quick fix, don't put any periods in your filenames besides .md.