Error applying retention policy in security & compliance - "Recipient not Found"

I have the same error, running the below command shed a little more light on the issue:

Get-RetentionCompliancePolicy -DistributionDetail | fl

The relevant part of the results:

DistributionStatus : Error
DistributionResults : {[Exchange]AllPublicFolderUnderRoot:Recipient not found: }

I disabled Public Folders in the retention policy, and now it has "On (Success)" as its status.  I wonder if the error occurs because we don't have any public folders, so the null trips up some code somewhere.  I just implemented the change, so I can't verify that the mailboxes were all put on hold.  At least the retention policy no longer has an error, so that's promising.