Calendar Invites Not Appearing Properly thru Hotmail?

[Arthur2015]

I signed up for my Apple ID with a hotmail account. I have an iCloud account with the same hotmail account. I've had this hotmail account for so long, I'd really like to keep it as my default, but I've noticed that hotmail seems to munge any calendar invites I send thru it. The invites just come thru as a file link, with no invite accept/decline/maybe buttons..is there a setting I'm missing somewhere? I tried logging into my account at iCloud.com, and I successfully sent an invite from there, so I assumed the problem is with hotmail.