Caption style being removed when post edited in iOS App

Expected behavior

When a new post is created and an image is added with a caption, going back to edit the post later would not change the style of the caption text to match paragraph style.

Actual behavior

If you don't add any text bellow the caption when you first create the post, the caption style remains. However, if you have not added any text after the caption and then go back to edit the post, the caption style changes to match the paragraph font.

Steps to reproduce the behavior

1. Create a new post and add an image to it.
2. Edit the image and add a caption.
3. Don't add any extra text bellow the image and publish.
4. Edit the post and add additional text at the bottom of the post after the caption.
5. Publish the post (style will change).

Tested on iPhone X, iOS 12.1.2, Aztec 11.4.1

Start by reproducing the issue in the AztecEditor-iOS app using the listed steps on an iOS device, then trace how an image caption is preserved when a post is edited and republished. Done means the caption retains its distinct style after text is added below it, with a regression test covering this sequence.