When you have a big team, Marker.io had a hard time fetching all your assignees.
We're now fetching the first 1000 assignees and then, if you start to type for someone in particular we're doing a call to the Jira API to get that person if he/she wasn't in the list.
Big kudos to Olivier for having made the More option modal much faster. Now you should feel a smoother experience in the editor.
Have a good time reporting bugs 👊