Cactus Growth has changed

I have a cactus farm and I noticed the rates went down. So I went up to check what had happened. The cactus seem to be growing and staying if they only have a single block next to them. Some of the "seed" cacti in the farm have also been destroyed for seemingly no reason, since there are no blocks next to them.

EDIT: The middle block did end up growing, it just needed time