That happened to me with the season 6 download when I first loaded it. I just redownloaded it and it worked. Just in case, make sure you're loading the save in 1.16.4.

Thanks for the advice I'll try that

This happened to me and redownloading the world didn't work :(

Remake the world if you have the zip file and make sure you are on 1.16.4 that fixed it for me