Pixelmon: Legendaries

Hello, I'm sorry if this is in the wrong area, but I had to say something and I thought this was the appropriate spot

Hello, I have a pixelmon server but no legendaries are spawning, i've been afk in a specific biome for an extra long time but nothing. What do I do?

With a command is possible, but the spawn rate of them spawning automatically is extremely low. And theres nothing I can change in the files.