Sending, receiving, and organizing email in Outlook.com
I'm having the exact same issue. I stupidly contacted customer support and wasted time on a call with a customer service rep. I told them I was just reporting what seems to be a glitch on their end but they kept trying to insist the error was on my part. It seems Microsoft and/or Google implemented an update that broke this feature. Please fix it ASAP as it is clearly negatively impacting many customers.