The question about FTB 8.0 compatibility with Windows 10 was explained by your answer. But there is another serious issue in this version: its File menu does not contain the possibilities "Save" (including dismissed "Save" icon) and "Save as..." and therefore is not usable.
So, my next question would be: Is the version 7.0 Build 7143 (which does not show the mentioned issue) also compatible with Windows 10?