Issue Summary

The user picker custom field doesn't show all available options when filtering users by group.

Steps to Reproduce

1. Add group filtering to a user picker custom field.
2. Add 25+ users to the selected group
3. Noticed that when the user clicks the user picker field, only a few options are displayed.

Expected Results

The user should be able to see 25 suggestions

Actual Results

Users can see ~5 suggestions.

Workaround

Start typing the name of users in order to see more available options to select