I don't think using dry ice or liquid nitrogen would help in this case.
It wasn't that it didn't freeze. It did freeze but it was similar to a fruity frozen drink thing, kids makes, in the way it froze. I don't know what they are called in english. When frozen semen has a sticky surface and even if you scrape it away and re-freeze it the sticky surface comes back. It's hard- like frozen things- but not completely solid I guess. I also didn't put it in ice cube trays but I doubt that would make a difference.