Minecraft Skyblock driving dealer doesn't spawn?

I'm currently playing Minecraft Skyblock… I need a moving dealer, but no one has been spawning for a long time… Is it possible that they only spawn on grass? Or what am I doing wrong? Because actually everything is made of cobble stone. It is also built from whole blocks. So there shouldn't be a reason why they don't spawn…

Just wait a few hours

I've been waiting a long time… But the traveling dealer can spawn on all non-transparent blocks, right? So he doesn't need grass or anything

After a Minecraft day, only one moving dealer spawns at any time. They appear within 48 blocks of a player. Initially, a spawn attempt is carried out with a 2.5% chance. If this fails, another try with a 5% chance of success will be performed after another minute. If this fails, the chance for all subsequent spawn attempts will be 7.5%. The cycle is reset two or three days after the traveling dealer has disappeared. The dealer llamas are also disappearing.

Thank you