Using core_v2_forumReply.List to list replies by a user in a particular group or forum

We're working on some achievement code and need to get a count of all verified answers by a user in a particular group.

The code for this is;

$core_v2_forumReply.List(null, "%{ AuthorId=12355, GroupdId=30, ForumReplyQueryType='verified-answers', IncludeSubGroups='True' }")

However it returns the system total for the user, not the total for the user from the group I specified.

If I try to filter it by ForumId, it's the same story.. and if I specify the GroupId and ForumId all in one, it's still the total for that user Disappointed

$core_v2_forumReply.List(null, "%{ AuthorId=12355, GroupdId=30, ForumId=21, ForumReplyQueryType='verified-answers', IncludeSubGroups='True' }")

I suspect that the .List command is seeing that I've specified AuthorId & ignores any other filters, which is really annoying, and isn't mentioned in the documentation.

Or is there something I'm doing wrong here? (hoping for an easy fix!)