Hi Jonas,
I tried this using ArcGIS Pro 1.4.1 (same build as yours) and VS 2015 Update 3, C# and can't find any problems. Having experienced similar issues in the past I usually traced it to another add-in, in which case removing all add-ins fixed the problem. In a rare case I traced an issue to left-over configuration files (in the Pro / bin folder) that I played with on previous installations of Pro and then forgot to remove before upgrading my Pro version. If you have done anything like this, I recommend to uninstall Pro, check for any left over files, remove them, and then reinstall Pro.