Google Analytics: All users are 'unassigned' even though I have specified userId -

i using universal analytics web tracking (analytics.js), , creating tracker so:

ga('create', my_google_tracking_id, 'auto', { userid: 'myuserid'); 

when examine network traffic google, of sends include query parameter: uid:myuserid

i have enabled user id tracking on google 'property', , have created userid report , non-userid report.

google's documentation states:

all reports in user id view display data sessions in user id assigned , related data sent google analytics. use different view see data sessions in user id not sent google analytics.

when @ user id view, see 'realtime' data, including content , events, if in other sections, audience/behavior/etc, none of them have content.

if @ non-user id view, 'realtime' data looks same user id view, fine, , audience/behavior/etc include content.

when @ audience -> behavior -> user id coverage report, says 100% of users unassigned.

any ideas how work docs say works?