HashCat just doesn't crack my MD5 hash with brute force

[DanielG]

Your hashes seem to be double MD5, so not just md5("abcd") but md5(md5("abcd")). 5259ee4a034fdeddd1b65be92debe731 is "asdf" for example.

If you look at https://hashcat.net/wiki/doku.php?id=hashcat you will see that hashcat supports this method as "-m 2600".