Answer
Since the code appears to run without error (you can see other side effects like an email being generated), this points toward a context/scoping issue rather than a missing grant — specifically, worth checking whether it's a site-access issue. Try running the same query without its WHERE clause to see whether data comes back at all when querying the full view unfiltered; if it does, the WHERE clause (or some implicit site-scoping the view applies) is likely filtering out rows in the Event Action's execution context that wouldn't be filtered out when the same query runs interactively from a custom RMB under your own logged-in session and site access.