worklist items expire after one destination user finishes

In our process, we have a client activity with multiple destination users. We want each destination users to vote (approve/decline). However, we're having trouble doing that. After one destination user finishes the worklist item, all the other destination users' worklist items expire. At the activity level, I have set "Create slot for each destination user" to true.

FYI, I am not using SmartForms, and am opening and finishing the worklist items via K2Rom.