What do you mean as invoiced activities? Billed time entries or issues?
I think, that invoiced products can be fetched by adding a new filter for products list like "Invoiced at". What do you think?

Kirill,

I have had a support issue open for over a month for simple Helpdesk configuration problem to get email automatically checking with a cronjob.

I've read the support KB article and it is not working.

Think you can get on your team to get it dealt with; I think a month is quite to long after how well the Redmine community has been to you.