Public Sign Up not working anymore

[Dan]

We recently updated to Jira Software 8.12.2 and are running JIRA Service Desk 4.9.0. For some reason, public signups on our portal no longer work. New users just get:

"We couldn't submit your request. Please refresh the page, then try again. Note that this will clear your request details.

If you have already tried again, contact your Jira Administrator."

Logs are not really showing anything relevant to this error. The public signup configuration on the project and in general matches properly, and it is set to Public not Private. Does anyone have any thoughts on where to begin? 

[Najjar _Innovura_]

Did you connect Jira to a writable user directory?

Sometimes Jira instance fails to create customers if it is not connected to any user directory with write permissions

[Dan]

It should just go straight to JIRA Internal Directory right, that what it was before. Where can I verify this for public signups?