Should bookmarks work in group footers?

system_migrated

I am using bookmarks to tag rows. This works fine with group headers, but erratically or not at all with footers, depending on whether or not I include a bound column. Without a column, the first instance of the footer row gets the bookmark, but subsequent instance do not. If a column is included in the bookmark expression, nothing is generated

Wondering if this is a bug or a feature.

Thanks.