Very often I habe a problem with my pointer: on a map I can't sometimes force my hero to use buldings or go where I want to (when I click on target nothing happens) - buildings, roads or treasures or creatures. The same problem is during battle - mostly i can't attack (ranged or meele) choosen creature! The problem is with pointer.
Windows 10 64 bit

Better post in the HOMM dedicated forum in GOG. You can always write to GOG support, too.