Editor: unable to select parent page in Parent Page dropdown in some cases

[worldomonation]

Steps to reproduce the behavior

Prereq. Possibly need a site with hundreds if not thousands of pages, like FG.

1. Go to My Sites > Pages.
2. Open a page.
3. Open the right sidebar.
4. Expand the Page Attributes section.
5. Begin typing in a page name. In the FG, try searching 'Quality engineering'.

What I expected to happen

Pages matching the search query are shown in a dropdown list.
The dropdown list remains static as long as the search query is not modified.

What actually happened

Not all pages matching the search query are shown in the dropdown.
The dropdown may briefly display entries that match the query in Step 5, but the entry quickly disappears.

This issue may be intermittent.

Context

Editing the FG.

Browser / OS version

OS: macOS Big Sur 11.1 (20C69)
Browser: Firefox Nightly 87.0a1

Is this specific to the applied theme? Which one?

Uncertain - it was reproduced on FG.

Does this happen on simple or atomic sites or both?

Tested on Simple.

Is there any console output or error text?

No.

Level of impact (Does it block purchases? Does it affect more than just one site?)

Moderate.

Screenshot / Video: If applicable, add screenshots to help explain your problem.

Screen.Recording.2021-02-03.at.12.59.05.PM.mov

[susanjanec]

Another report on 4030839-zen

[synora]

Triaged. I can replicate testing this in the FG. It works as expected on my test site with 8 pages.
Note the report above in 4030839-zen has over 5,000 pages.

[AtrumGeost]

Got another report. The (simple) site has 190 published pages:

4415334-zd-woothemes

Asked them to set the parent page from the Quick Edit option on the Pages WP Admin dashboard.

[cuemarie]

Closed #76170 in favor of this report. That report was opened for this P2: p2EDhh-1Vs-p2 , where this problem continues

[github-actions]

Support References

This comment is automatically generated. Please do not edit it.

• 4030839-zen
• 4415334-zen
• 7121105-zen

[cuemarie]

Some updated notes from @Greatdane on #76170 :

This is a hard one to reproduce, as you need a complex site with many pages and a lot of parent and child pages. But it seems like while all the children and parents will show up in wp-admin, when you search for them in the calypso-based page editor, they will not show.

Steps to reproduce

1. Have a site with many pages, and parent/child pages.
2. Create a new page, and search for the parent page within the page editor
3. The parent page will not show up.

What you expected to happen
The parent will should show up

What actually happened
The parent page does not show up after a certain number of child/parent pages are created.

See this post for an example: p2EDhh-1Vs-p2

Workaround is to use wp-admin quick edit on the pages dash to select the parent page (it shows up there).

---

Notes from Re-Triaging this

📌 SCRUBBING : RESULT - Replicated / Could Not Replicate / Uncertain

• Tested on Field Guide (AT) (as suggested in above report) – Could Not Replicate
• Tested on P2 ( ATU ) - Could Not Replicate
• Simple Site - Needs Further Testing - crowdsourced for some help here: p1682632930719999-slack-C03TY6J1A

📌 FINDINGS/SCREENSHOTS/VIDEO
Wasn't able to replicate this in AT or P2 environments - see video below. I think we need to try to replicate on a simple site as well. The latest customer report (p2EDhh-1Vs-p2) is on a Personal Plan site.

Screenshots/Recordings

RTBAiO.mp4

📌 ACTIONS

• Assigned to Cylon
• Possibly Related: https://core.trac.wordpress.org/ticket/46294

[radtechgh]

another report: 7121105-zd-a8c