Bug - featured image - show caption feature not working

[SophieAmnesty]

Describe the bug
When I try to un-hide the featured image caption, it doesn't seem to be working.

To Reproduce
Steps to reproduce the behavior:

1. add a new post and add a featured image with content in both the copyright (description) field and the caption field.
2. go to appearance settings, post options and un-toggle the 'hide featured image caption' setting.
3. publish/preview post and see that the caption is not showing on the front end.

Expected behaviour
I should be able to show the featured image caption on the front end using the appearance settings.

Actual behaviour
the change doesn't seem to come through on the front end.

Link to a page where the bug is reproduced in isolation (optional)
https://isaidotorgstg.wpengine.com/en/latest/news/2025/01/caption-on-featured-image-test/

Platform:
https://www.whatsmybrowser.org/b/UILZ7

Additional context
wasn't sure if it could be related to this: #505