In recent times I was working with this developer customer. They created a custom application using Outlook Object Model (OOM) API – their app tries to create a new message programmatically with attachments. They notice the newly created items fields (such as the CC, BCC and TO) overlaps or garbled. Based on my tests with latest Outlook 2016 (1804/1805 build and above), the issue is not reproducible. So if you see the issue, please make sure the get the latest Outlook build or even Office Insider – Monthly Channel, get the latest build and test the scenario.
Hope this helps.