C:/"Program Files (x86)"/Lua/5.1/luac.exe -o C:/Users/admin/Desktop/IRP/5.1/##_asmh.BOC - "C:/ProgramData/Calico Pie/Family Historian/Plugins/##_asmh.fh_lua"
The single minus sign in luac command line means "read input program from stdin" (or "stop handling options and process stdin").
So, luac waits for your input from the keyboard.
Remove the minus to read your input file.