I have had the same problem with Outlook for ONE YEAR! The workaround was to create a 'tempinbox" under the normal Outlook inbox and create a rule that would send anything sent to the incoming account to the tempinbox. It works but anything sent to s distribution list goes to the normal Outlook INBOX. It was either the workaround or use webmail.
I agree with your comments on support. My 'cox' modem died last week. I bought another one at the Cox Authorized Dealer in our town and spent well over an hour on the phone with support after I installed the modem. The lady I was talking to couldn't swap the modem. My phone finally disconnected. I called back and got a guy named Kyle who knew what he was doing! Took about 10 minutes to fix the issue. It depends on the support person. They tend to want to get rid of you rather than troubleshoot the issue. A few days before the modem died completely, Cox support told me it was my router. Unbelievable!