Help Needed: Issues with Email Waterfalls and Column Merges

Anyone help re issues related to work email waterfalls and column merges? 1) i ran the standard find email waterfall, and initially had the default work email column to aggregate across vendors. Some emails weren’t picked up so i added columns using the structured JSON results. Now - the standard merged waterfall results display no emails, but i also can’t use a custom merge to merge the multiple email columns created. Can anyone help?