The Advanced Find filters (/Report filters/View filters) can be fickle to work with if you’re starting from an existing filter. This is especially true if the filters contain an AND or OR clause:
So, if you have a complex filter and want to add to AND or OR groups, without deleting those groups and starting from scratch, it’s actually very easy to do:
Select the “AND” or “OR” grouping (Note that you have the option to change this to the opposite kind of grouping).
Select “add clause” to add another line within that group:
Save your Default Filter (for Reports) or View (if in Advanced Find) for future use.