Can not add widget to specific Page Layouts

[gizmocn]

Try to add widget to specific page layouts, but in admin panel no page layouts list is empty

Preconditions

1. Magento 2.1.6
2. PHP 7.0.15

Steps to reproduce

1. Magento Admin panel -> Content -> Widgets
2. Click "Add Widget" button, then select any widget and theme.
3. Click Add Layout Update button and then select Display on to Page Layouts

Expected result

1. In Page dropdown, All Page Layouts should be list out.

Actual result

1. Actual, there are no Page Layouts listed.
   

[AlexWorking]

Hello, @gizmocn. Based on Your issue an internal ticket was created - MAGETWO-70278. You'll be informed after the issue is resolved. Thank's for applying.