Hi @Daniel86,
This seems to be a bug in the editor markdown. On the other hand, the markdown version does not allow specifying the target property. Unfortunately, we are only solving critical bugs on Taiga 6 because we are focused on the development of Taiga Next.
Currently, the links work only with the full URL, or, if you are on a wiki page and want to link internal pages, you can use this format:
An [[example-one]] or [[example-two|Example 2]] of wiki links.
Cheers!