Yeah, I agree with @ThinhDinh. JavaScript and/or the Format Date column both work perfectly fine most of the time. But under some circumstances both can fail on Safari. And when they do, it can be a PITA to try and figure out what went wrong.
I always use Math columns for this sort of stuff. Year(Date) to get the Year, then Month(Date)-1 to get the Month Index, followed by a Single Value to get the Month Name. It’s a bit more work, but I’ve never seen this method fail.