"Signer" not an option in template

I'm trying to make sure that all fields are correctly assigned, and I've discovered something odd about some of my templates.

Most are fine, but for several, the Recipients section doesn't show "Signer" as an option.  I can select Sender, Participant 1, Participant 2, or Anyone.  Signer isn't there.

Is there any way to make it show up?  Any ideas about why it isn't?

Edit: Figured it out.  Those were the ones where Name/Title/Date fields had been added, but Signature fields hadn't.  *headdesk*

Edit 2: That was not the issue, that was a coincidence.  However, if I send out two templates at once, one with Signer fields and one with Participant 1 fields, it correctly assumes they should all be going to one person, so I'm not as worried about correcting this error.