The invoice template "Professional 1" does not have unit prices. You'll need to change your invoice template to "Professional 2".
Please go into Settings->Invoice Defaults, then change the default
invoice template to "Professional 2". Then press update settings. Then
close Invoice Expert. Then reopen Invoice Expert and create a brand new
invoice. Make sure the template has defaulted to Professional 2, add
some items and then click print, you should see the unit
Sometimes existing invoice that have already been printed with an old template don't update to the new template until you press Add/Update invoice multiple times. Basically when you press print we keep a cached copy of the last printed invoice.