The Macro body only shows an empty extension frame instead of a placeholder when editing the macro settings

Issue Summary

The Macro body only shows an empty extension frame instead of a placeholder when editing the macro settings.

Steps to Reproduce

 The issue has been reproduced with a specific macro, but other macros might be affected as well.

1. Make sure the "New approach to Confluence Cloud macros" is available on the site
2. Add a Macro to a Confluence page (e.g. the "Miro embed for Confluence")
3. Edit the Macro settings with the page in editing mode (e.g. Enter an invalid or an empty URL)
4. Save the page
5. Re-open the page in edit mode

Expected Results

The placeholder value loads.

Actual Results

An empty extension frame loads (see CONFCLOUD72277.mp4 )

Notes

The placeholder content loads when the page is open in view mode.

Workaround

Reload the page for the placeholder to load.