> Can you update to 16.3 or 16.3.1? I think 16.3 was the version release for > .Net core 3 and C# 8. >
I returned to my normal work PC which has VS2019 16.3.1 and all problems have vanished. Now I see that the machine I was running my tests on earlier today is 16.2.3. D'oh! (I didn't realise it was behind). I also see now that the Language version is disabled and says "Automatically selected based on framework version" with a link below to explain <https://docs.microsoft.com/en-au/dotnet/csharp/language-reference/configure-language-version>. This all makes sense while we're wobbling between Full and Core frameworks due to combinations that won't work. I see there are tricky ways to override the restrictions though. *Greg K*