Did you get to the bottom of this? This could be several different things, so hard to say without looking at your system. Couple of questions:
- are you using msvc and not mingw compiler?
- are you using 32 or 64 bit windows qt kit?
- when you build and run the app, does everything work? or is it just a console warning in the IDE?
- Do you see any logs like the following in the Qt Creator general messages console log? This would indicate everything was found ok.
Project MESSAGE: ArcGIS Runtime for Windows (x86_64)
Project MESSAGE: Version 100.5