> This is because Emacs diary only looks 
> `icalendar-export-sexp-enumeration-days' days ahead from now when 
> exporting non-standard diary sexps. By default, it is 2 weeks. 
> So, you would see the anniversary in icalendar if it were 2 weeks from 
> now.
> 
> You can increase `icalendar-export-sexp-enumeration-days' to get the 
> anniversary occurrences exported up to that number of days ahead.

The variable `icalendar-export-sexp-enumeration-days` is indeed set to 14.   However, even entries of the form 

    * Test 1
    %%(org-anniversary 2023 07 22) Test1
    * Test 2
    %%(org-anniversary 2023 07 24) Test2

do not get exported today (2023 07 23).  

> Also, `org-anniversary' does not support %d. AFAIK, it is only working 
> for built-in sexp types, which are handled specially.

    %d works perfectly in the agenda view.

Marcus