I like to have an index markdown file and to sort this file to the top of a group I usually use an underscore. However, I just noticed that if a file starts with an underscore, the wikilink breaks.
You can reproduce this easily by creating a markdown file in DT, typing a [[wikilink]] and then change it to [[_wikilink]] and straight away the hyperlink will disappear and it will no longer be clickable. I have tried with a few other non-alphanumeric characters and the result is the same.