Why are signatures showing with no frame?

Issue

Some completed documents contain a signature with no frame.
 

Cause(s)

If signing is performed via a Mobile app, there is no chrome (DocuSign frame) around the signature.
 
DocuSign Frame - Signature
No Chrome
Sample signature and initials without the frame
 
With Chrome
Sample signature and initials with the frame

Note: DocuSign Admin | Signing Settings for the DocuSign Signature frame do not apply to signatures applied in a Mobile app.