Mutator: unrecognized by oathkeeper (v0.17.5)

i follow the example ->

except im using v0.17.5/Latest, instead of those beta version

but i always get the error

level=error msg=“Unable to update access rules from given location, changes will be ignored. Check the configuration or restart the service if the issue persists.” error=“json: unknown field “mutator”” file=“file:///rules.json”

And i also found that Mutator only work at v0.17.0-beta1

so v0.17.0-beta1 is newer than v0.17.5?? What the hack of this version logic?