I am currently testing ICT's suggestion to see if it more accurately captures UserID events so I have no comment on whether or not it works at this time.
However I did have reasonable success with the following filter. I am running a PA-3020 on 8.1.12, and a SZ-100 on 3.6.2.0.222. I have avoided the 5.x release like the plague due to stability issues which is possibly related to the issues you are having, difficult to say.
Regardless, here's what I have used:
Event Regex: @@206,clientAuthorization,
Username Regex: "userName"="([a-zA-Z0-9\-]+\.[a-zA-Z0-9\-]+)(?:@[insert your domain here]\.[insert .com, .ca, whatever your tld is here])?"
Address Regex: "clientIP"="([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})"
Note the bold portions above, insert your domain and your TLD where the bold type is, making sure to not include the opening and closing brace as well
Your mileage with this may vary but if nothing is working for you now it's worth a shot. I know that Ruckus seems to change the event to look for with every firmware release. This has worked fairly well for me for the entire 3.6x release.