Command Palette switching to site-editor doesn't work

Quick summary

Using the new command palette in Gutenberg 19 to switch from the post-editor to the site-editor doesn't work - the site-editor doesn't load and an error message is displayed instead.

Presumably this is related to the post-editor being iframed and the site-editor not being iframed as I get this message in my console:

The loading of “https://deantest08.wordpress.com/wp-admin/site-editor.php?postType=wp_template&postId=pub%2Fblank-canvas-3%2F%2Findex” in a frame is denied by “X-Frame-Options“ directive set to “SAMEORIGIN“.

Going from the post-editor to the site-editor does work.

Steps to reproduce

Open up the post editor at wordpress.com/post/:site
Press ⌘ + k to open up the command palette
Type the name of a template, e.g. index
Press enter

https://github.com/Automattic/wp-calypso/assets/93301/4e9c08f3-6967-4eff-b6af-d25d12efcc51

What you expected to happen

The site editor to be opened up showing the index

What actually happened

I got an error in the browser:

Impact

All

⌘ + k isn't hinted at in the post-editor, it requires that you learned it in the site editor first.

Available workarounds?

Yes, easy to implement

Just use the normal way of switching templates - by navigating using the menus to the site-editor.

Platform (Simple and/or Atomic)

Simple & Atomic

It doesn't affect .org sites.

Logs or notes

Reproduced on Firefox and Chrome.

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

Tested on Simple – Replicated
Tested on Atomic – Replicated
Replicable outside of Dotcom – No

📌 FINDINGS/SCREENSHOTS/VIDEO

Replicated as described! While my self-hosted site can move from the post editor to the site editor, WordPress.com sites (simple and atomic) encounter a browser error.

Screenshots/Recordings

Atomic Site

https://github.com/Automattic/wp-calypso/assets/27249804/fe8232a1-5901-4a8a-9989-3555eeb382e0

Self-Hosted Site for comparison

https://github.com/Automattic/wp-calypso/assets/27249804/552c8860-2342-4fee-828f-e2520b7fb4ec

📌 ACTIONS

Assigned to Non-Urgent
This has also been flagged here by OP: p1685629388373389-slack-CBTN58FTJ

Automattic / wp-calypso