Obviously incorrect hit counts in FortiManager

We are using FortiManager v6.2.7 GA Build 1398 to manage 50+ FortiGates. We would like to clean up several rules that aren't used anymore, however the hit counts on FM for some rules are obviously wrong.

Some have exactly double those counts. Is there a way to manually clear those counts so that when the FG reports the count, it will start keeping track accruately? The only thing I've found is that supposedly clearing the count on the FG will update the FM count, but that doesn't seem to work.

Thanks for any help.