Discovered bug on Twenty Twelve theme under WordPress 5.6!

Hi! I discovered a bug on Twenty Twelve theme when being used on WordPress 5.6 (last version). On image.php, the image dimensions doesn’t appear.

Follow these steps to reproduce the bug:
– Install WordPress 5.6 (last version)
– Install Twenty Twelve theme 3.3 (last version)
– Don’t install any plugin.
– Add a picture to a post
– Go to the image attachment page

On image.php, the image attachment page, the image dimensions won’t appear. Instead of “1221×124” you will see only “x”.

If you could check this and solve this bug, would be great ??

Thank you!