It seems that Hazel stopped working after applying 10.5.2, which is an essential fix for me.
I have tried to recreate some of my rules to see if that would help, but it seems there is something that Hazel relies on that must have been changed by 10.5.2:
hazelfolderwatch[1715] Caught exception in rule evaluation of file <file name>: Could not retrieve metadata for file: <full path to file>