Thanks Chris! Appreciate your assistance. The error seems to be resolved. I believe Auth0 was also at issue.
With respect to mod_security settings, the hosting provider has reverted that:
_however, upon review with our higher tier we were not able to locate any rules regarding Cornerstone URLs. If you could clarify further on the nature of the request we would be happy to make the requested adjustments. _
We will be happy to check further on your behalf, but will need to be able to replicate the error to be able to accurately review the servers logs. Could you please also respond with the replication details which would allow us to generate the error on our end (including any necessary login information to be able to access the error). We will be happy to check for any Mod Security errors being generated for additional information.
Is there any details that I could forward them to assist? Many thanks.