Doesn't work w/ Subscribe To Comments?

Looks like this plugin has some kind of conflict with Subscribe To Comments plugin. I have an author who is restricted to his category. Comments posted in his posts are not mailed to him (even though he’s subscribed for them – this has been checked multiple times). Comments posted in all other posts are mailed OK without any problems.
Is there anything that can be done about it?

http://wordpress.org/plugins/author-category/