I've encountered a bug that has some regularity/reproducibility. I don't know if it's already known, but I couldn't find anything similar posted here.
When playing Her Finest Hour repeatedly, in the same game session (which I've been doing today because I want to complete it with perfection), after some repetitions, the target groups (F5, F6, F7, etc) stop working. The only way to fix it is to close FS2 entirely and open again. I didn't count, but I'm thinking it's triggering after 10 or so attempts on the mission, maybe less.
I'm playing on Windows 10 64bit, with FSO 3.7.4 AVX Stable build.
No mods other than BP Complete and MediaVPs 2014 loaded.