Hi all,
We are currently using OBIEE 11.1.1.7.171017 and have just started to notice a strange issue when trying to use the CASE WHEN formula inside analysis formulas, prompt SQL and BIP data models.
The error returned is as follows:

We also get the following error message in Chrome Tools:
Failed to load resource: the server responded with a status of 500 (Internal Server Error) at /analytics/saw.dll?ResolveActionXML
Another error in the logs:

We can reproduce the error easily by attempting to create a formula using a "case when" statement.

The full text of that error message is as follows:
There was a problem retrieving the response data: Internal Server Error (500).
Third-party server not responding.
The resource you have requested is located on a third-party server. WebSEAL has attempted to send your request to that server, but it is not responding.
Explanation
This could be due to the third-party server being offline, or to network problems making it unreachable. The problem is not with the WebSEAL server itself.
Solutions
Retry your request later, or contact the system administrator for assistance.
Both app and OHS servers have been restarted and no changes were made to either on the day the error started occurring.
Any help would be greatly appreciated.
Thanks in advance,
Adam