I have created a Select - Multiple field.  If I change the "Separator" value from the default of "," to anything else, the field is not displayed in the Content (i.e. in the front-end the field label and data are skipped and there is no error message).  I have tried changing it to a period, slash, a pipe character (i.e. "|"), a letter, a space, a hyphen, or even a comma with a space after it (e.g. ", ").

In my opinion, the "," doesn't make the result look very good.  Compare:
Drama,Action
Drama, Action or Drama/Action  <- I think either of these looks better than the comma with no space

If I am stuck with the "," how can I override the rendering so it looks better?

Thanks!