Dave - with version 4.4.x, we moved the moderation to be module specific (this was done as a security measure)... What this means is that if you for any reason you delete the instance (on a page) with which the feedback was created, you'll not be able to moderate any of the posts anymore.
I obviously understand that this is highly undesirable which is why this is now an optional check in the new (5.0) version but that doesn't solve your problem.

If you're interested in making it work with your specific scenario (and UNDERSTAND the ramifications of turning off this check), then you can modify the stored procedure UpdateFeedbackStatus to remove the where clause for the ModuleID.

Current value:
 IF @Status = 4
 DELETE {databaseOwner}[{objectQualifier}Feedback] WHERE FeedbackID = @FeedbackID and ModuleID = @ModuleID
ELSE
 UPDATE {databaseOwner}[{objectQualifier}Feedback]
 SET    Status = @Status
 WHERE FeedbackID = @FeedbackID and ModuleID = @ModuleID

New with changes
IF @Status = 4
 DELETE {databaseOwner}[{objectQualifier}Feedback] WHERE FeedbackID = @FeedbackID 
ELSE
 UPDATE {databaseOwner}[{objectQualifier}Feedback]
 SET    Status = @Status
 WHERE FeedbackID = @FeedbackID

Please understand the ramifications of making this change.

If you have different feedback instances on different pages that are setup to be moderated by different people, they'll now have the ability to moderate each other's posts.

If this is not a concern, you should be able to make the change and get your moderation to work.