Outlook.com Emails not being Marked Read?

So I've been testing out Outlook.com to see if I can use it as my primary email. I do like the service, but I'm having trouble with messages being marked as read. I'll read an email on my phone (a Lumia 900), reply to it, and then it's immediately marked as unread on my phone again. My guess is it has something to do with the way Outlook.com is grouping conversations, but I'm not really sure on that. Anyway, I was wondering if anyone else is having similar issues. I did report it using the Outlook.com Feedback tool, so I'm hoping it gets fixed for me soon.