Well - I finally have somewhat of an answer to the elusive degree symbol bug. As I’m trying to build the app with Qt6 and having to switch to the MSVC build kit - which I’m still having issues with 
- I decided to take a step back and see how my system builds with Qt 5 and the MSVC19 64 bit kit. It should be noted that I’ve been using the GCC MingW kit… which has NEVER given me the the degree symbol error. I got the app to build with MSVC, but lo and behold that stupid bug is there! So it’s not an XML or UTF-8 or time zone / locale issue… it’s an issue with building with Microsoft Visual Studio! - which is what the release builds are using. So the question is - is the issue on Qt’s end or MS’s end?
