Currently, when a custom field of checkbox type is set up in a tab in the old issue view layout, it's shown in the right-hand-side panel when the issue is displayed in the new issue view. Clicking on it loads another view where the field is shown. Clicking on the field shows the checkbox options already selected and the options available for further selection. All this information is displayed in a very compact, rather congested space where options are truncated and two scrollers are shown in very close proximity.

See: custom_field_newissueview.mp4

The suggestion is to widen this space where these custom fields are shown.