Hi,
Been running Jira Service Desk (jira 7.12.0) for a while now, our customers have previously been able to log in successfully until this morning.
Regular Jira users can log in ok to Jira/Confluence/BitBucket/Bamboo etc, no problems there at all.
Customers do not get an error message, the login screen just hangs and the spinner keeps churning on forever (seems all customers affected):

In the security log file I found:
/servicedesk/customer/user/login login : '[username]' tried to login but they do not have USE permission or weren't found
Using Jira Internal User Directory, account exists and is active. Does not need any groups because its a customer account.
We have not made any changes in the permission scheme.
Tried upgrading jira to 7.12.1 (which upgraded JSD) to see if that will fix it but it's still the same.