iCal event URL no working after upgrade to Yosemite!

After upgrading to the latest version of Yosemite (10.10.2), the event "URL" field has become useless. After launching iCal, the URL link in a previously created event (before upgrading to Yosemite) works once, but after using the link to open an email, each subsequent event URL links the same email. The problem doesn't occur on my iPhone 6 Plus running the latest iOS. Also, I can't create new links to emails ... the moment I finish typing "message:" the text gets replaced with "Show in Mail..." and I can't add the Message ID link.