I made a new pet, then swapped names with my existing pet, before using a Genderless Berry on the new one. However, it does not seem to have worked at all, even though I'm sure I used it on the right one. I don't know if I really did make a mistake, or if the site hadn't updated the names yet and I used the wrong one because of it.. I just don't want to have to spend another 10 million SP, so I wanted to know if it was an error first. And yes, I already tried clearing the cache multiple times.

Did you use the "use on" or "feed to" option? Because the feed option doesn't change the pet's gender

I made sure to use the "Use on" option.

Anyway, it seems to have happened now. Either it took time like some things here do, or there was an error that someone fixed.