Error: 500 Internal Server Error - Call to a member function decryptBeforeOutput() on null

Scenario to produce the error consistently:

• An admin is logged into the CP
• Admin creates a survey, adds themselves as a participant, and sends an email invite via LS
• Admin receives the email invite and clicks the link to the survey as any respondent would
• The survey opens in the same browser of which the admin remains logged in with an active session
• When admin (respondent) views the survey page, they see the error noted above

Scenario that cannot reproduce the error:

• All of the above with the exception that the admin logs out before attempting to view the survey
• OR the admin does all of the above and views the survey in a different browser

Please advise.
Thank you