No reason a batch can't handle file paths containing spaces, as John says, but if you don't want to fix the batch file an alternative is telling Opus to pass short names to the batch instead of long names. (It's just a different argument code.)
Not if I understand what you're trying to do. An {F} control code will send the fully qualified names (meaning including full paths and double quotes if the file names have spaces) of all of the files and folders you have selected in Opus to your batch file in a group.
An {f} is similar but it will launch a new instance of the batch file one at a time for each selected file or folder.
So if {F} is working but not for files with spaces in the name, try changing {F} to {Fs} or {allfilepathshort$} to send the 8.3 short names with paths to your batch file.
Or you could tweak the batch file as mentioned above so it will process file names with spaces.