Thank you for reaching out to us. Unfortunately when we originally tried to roll out the campaign search functionality, there were some severe glitches that caused the engineers to hold off on rolling it out to everyone.
I've made sure to attach your case to the applicable service request and submit it to our engineers. They will reach out if and when there's an update. In the meantime, you do have the ability to filter by date from the My Campaigns screen.
If you need any further assistance feel free to reply here or create a new thread, and we'd be happy to assist.