Action wizard to batch signature certificates crashes

I cobbled together a custom action using JavaScript that will automatically apply the users signature certificate and appearance to a named signature form field. I am not a programmer and put this together about 5 years ago. We have one user that uses this action daily on 10-30 pdfs. The action has been serving our needs since then but recently the action now crashes while processing the first PDF. The signature is applied, but on re-open the certificate has problems and is not recognized as valid. The rest of the files in the directory are not processed at all. The same action processed on a single pdf (using currently opened pdf) completes with no issues.

Hoping to find a solution to this, 10-30 pdfs doesn't seem like a lot, but would take up a non-insignificant amount of time to process individually.