Can't see all contacts when I am creating a new job #

I run MYOB essentials and I have many customers recorded in my contacts.  My problem is when I open a new job # I can't select any contact that starts with anything after the letter M??  I know the others are there but they will not appear in the drop down nor do they start when I type them in.  If I continue it just records the job # with no linked customer.  It's like there is a filter on it or something.  Either way I can't record a linked customer