Thank you for reporting this, I will open a ticket for this issue with our team.
We are designing our service desk so for customers its fully email based. If a customer sends an email in which contains a ":)", any text following the smiley is not logged in the ticket details. The smiley is converted to a graphic automatically in Outlook, which I assume is causing the issue. I can't find a way to easily change this behaviour in Outlook, as it's built into the autocomplete settings. We will have 50 or so staff using the service desk so its also not something we can go to each PC and manually change, and GoToAssist should be able to input the entire email message text whether there is a smiley in it or not.
I also found an article from mid-2017 detailing the same issue, so its been brought to attention before:
Can this bug be fixed?
@Mark_P [Final Update, 20/20] There was a compatibility problem found during testing, and we must delay this fix until we can confirm there are no further conflicts. New ETA: 1/15/19