Solved
Project>Build Project greyed out/nonfunctional
Why does this happen ? Could this, in part, be due to me not knowing whether to choose "new C project" vs "new C++" project?
Using:
STM32CubeIDE 1.5.1
Build: 9029_20201210_1234 (UTC)
OS: Windows 8.1, v.6.3, x86_64 / win32
Java version: 1.8.0_272