Late Waitlist SIR?

So I just checked my UCSB portal (May 29) for the first time in about a month to find that I was admitted off of the waitlist on May 5. I was beyond surprised because I thought I hadn’t received an email about my acceptance. However, on closer inspection, I actually did get an email stating that there was an update to my admissions decision (on May 5). Due to my late discovery, I missed the SIR deadline of May 11. Could I still attend? It would be devastating for me if I didn’t have that option. Thanks for your help.

Contact the admissions office ASAP and explain the situation. They might grant an extension.