Nudges - existing tokens to retrieve Recipient name in email body are not working after 26C

We are seeing email alerts that contain tokens used to retrieve the email recipient's name failing or returning null after the 26C upgrade in most Nudge Event Alerts.

For example, in Nudge to Alert Journeys:
${AlertUtils.userName(RecipientUserName).DisplayName} is failing with the following error:
groovy.lang.MissingMethodException: No signature of method: oracle.apps.hcm.common.core.alerts.AlertUtils$A...
and
${RecipientUserName} is returning null.

Ultimately, our goal is straightforward: we need a working expression or token that returns the recipient's name in the email body, regardless of whether the recipient is an Employee or a Line Manager. (We need to send alerts to employees and managers when a journey is not completed by an employee.)