I've seen it have issues with some non-English characters. Try changing the file name to have only letters in the English alphabet, relink the newly named file in AE, and then track it in Mocha. See if it works.
The main bugs that I know about have to do with using characters that are not in the character set of the language in which you're running the software. So, if you're running the software in English, it's safest to use only alphabetic characters in English.
Hi Todd ans Szalam, thanks for the answers.
I figured it was a bug, is there any way to know if its being fixed? Our sizeable footage library contains some amount of scnadinavian letters, and since the library footage is being used in multiple places, im a bit scared to start changing filenames. I can work with tracking inside AE for the time being if this is a bug that i know is going to get fixed some time soonish.