I have a form which populates a manager dropdown field from the cf_users table. Most users are able to select the manager but there are random employees using either a Mac, Windows, iOS and IE, Firefox, Safari, Chrome, whatever...the manager field is blank for some. This field is required for submission and routing.

Lookup being performed:

I have a separate process that performs this same lookup, only this field is a single line field and requires the user to start to type a name and then select the appropriate name when presented. This field/form works for everyone, every time.

Has anyone experienced this issue of a lookup working for some but not all?