Using Outlook for iOS for personal email and calendar management
This problem is very real and a nightmare for business folks constantly on the move. I am currently experiencing the same issue with the latest iOS version and Outlook app.
The only workaround is to paste the conference code in the body of the invite, but that doesn't alleviate the pain as one must open the invite and scroll through to find the number. This isn't safe for those of us driving.
If your standard Apple Calendar app is in sync with your Outlook calendar the location dial in will work, but you're now using two apps...
Microsoft, please look into this and send out a patch ASAP.