This will occur if the hash is entered incorrectly, i.e. hash delimiter is missing.
This will occur if the hash is entered incorrectly, this article will cover possible scenarios that may result in the error as well as how to enter hashes into a policy.
Below you can see the hash, notice the beginning of the string, it is missing the delimiter (S:/M:) (fig1) it should have a delimiter that corresponds to the algorithm used for the hash (fig2).
This will occur if the hash is placed in the main page of the rule without the delimiter. (fig3).
The fast solution if the delineator is missing is to edit the value by placing either an S: or M: in front of the hash.
The designed way to input/edit a hash is with the button as outlined below (fig4 -5).