Enable Automatic Status Updates in Salesforce not working

In a Salesforce sandbox, I have had the Adobe Sign integration working for quite a while.

Yesterday, it appeared to stop working without warning and when I signed into Salesforce, it appeared that my password had expired. I updated it, but automatic status updates continued to fail.

I went into the Adobe Sign Admin page and clicked on Enable Automatic Status Updates but I keep getting this error when I do. Can anyone help me resolve this?

Error message:

Sorry, we were not able to process your request.

Please try again later.

If this error persists, please contact support.