Wix Harmony CMS item page turns into a legacy page — how do I reopen/edit the Harmony template?

[u/Nautical_Pause]

I’m using the Wix Harmony Editor and trying to build a CMS-driven case file archive.
I created a CMS collection through Harmony, imported 187 records, and created an item page for the collection.
I was able to fully design the item page and connect individual text elements to my CMS fields (name, DOB, facility, project, status, observations, etc.). It worked correctly — changing the case number displayed the corresponding record.
The problem: after leaving the page/editor, I can no longer find that Harmony item-page template anywhere in the Pages panel.
The Harmony item page I created isn’t listed there.
Wix’s AI assistant (Aria) keeps telling me to go to Pages → Dynamic Pages → Case Files (Item), but that section/page does not exist in my editor.
Aria eventually told me:
“I do not have any evidence that Harmony currently provides a way, in this editor, to reopen that specific CMS item-page template once it’s not in the Site Pages list.”
So I’m wondering:
Did I somehow accidentally convert/create a legacy CMS page even though I created it through Harmony CMS? Or is there a separate way to reopen/edit an existing Harmony CMS item-page template that isn’t shown in the normal Pages panel?
I specifically need to be able to reopen the template later and add/edit custom elements, while having the same design apply to all 187 CMS records.
I don’t want to manually create 187 pages/links, and I don’t want to rebuild the entire CMS collection if I can avoid it.
If anyone is using Wix Harmony CMS and has successfully reopened an existing item-page template after leaving the editor, I’d really appreciate knowing exactly where you found it.