I work for a multi-disciplinary engineering firm and use several versions of Revit at any given time. I have recently opened an existing project in 2016 to find that it loads incredibly slowly and has graphical errors such as not showing the toolbars until I move the cursor over them.
I have worked in 2017/2018 + 2019 in the same day and there are no issues with any of these versions. I have also opened up other models in 2016 and the same issue occurs, so it doesn't appear to be a corrupted model issue.
Any ideas?