Restore Lost WordPress Multisite Page

My WordPress multisite dropped a single static page right after I swapped the primary domain. The rest of the network is still up, so I suspect a mapping or database reference got left behind during the change. I did tweak a couple of other settings around the same time, which could also be contributing to the issue.

I need the missing page to re-appear exactly as it was—same URL slug, layout, media and internal links—without breaking anything else in the network. You’re free to use wp-cli, phpMyAdmin, Search-Replace-DB, or whatever tools you trust, as long as the fix is clean and reversible.

Deliverables:
• Page fully restored and loading on the new domain
• Brief outline of what caused the disappearance and the steps you took to resolve it, so I can avoid a repeat

The sooner this is patched the better; I can give immediate access to the dashboard, hosting panel and backups.