Workflow - signatures in pdf

Hi there. I have had this occur twice in the past week with no obvious cause. I am wondering if anyone else has experienced this with their workflows. It seems that randomly some signatures don’t flow through to the form, whilst others do.
I need signatures on forms for compliance purposes.
Within the form, if there is a name in a cell then their should be a corresponding signature. I produced a test form and did not change anything while I filled in each signature. Image below. Any advice would be appreciated.
Any duplicate names was deliberate.

@Phil Any thoughts what could the reason for this behavior?

Tx Aleksi. I have had hundreds and hundreds of signatures on workflow email docs perform faultlessly over the past few months, but 2 in one week may not be isolated. Cheers

The User in the first occurrence did not change anything from previous days form completion. The image I posted in the initial post above, I generated from the App editor on my PC. Cheers