Why does blank line of white space suddenly appear within a paragraph & best way to fixed

[Editorial-Design]

I am doing the design, layout, and typesetting of an 88-page magazine using InDesign (2025) 20.4.1 with a M4 Mac mini and MacOS Sequoia 15.3.2 (24D81). The InDesign file is located in my hard drive Dropbox folder synced to my Dropbox on the Dropbox website.

After reflowing the same text into the same text box for the third time, suddenly a paragraph in the text has a blank line space in the mdidle of a paragraph, like this:

"After reflowing the same text into the same text box for the third time,
[empty line space here]
suddenly a paragraph in the text has a blank line space in the mdidle of a paragraph, like this."

After much trial and error, the only way I figured out how to fix this was to insert new parent page into the document and flow the same text into a new text frame in the new document page based on the new parent page in the document. Then I deleted the text frame with the bad paragraph loine spacing.

Does why might have this happended?
Is there a better way to fix?

Thanks so much.

[Mike Witherell]

Editorial Design,

Did you look at the text while Type > Show Hidden Characters was turned on?

Did you vault the text open into Edit > View in Story Editor?

And you are not working in Preview mode; just Normal mode?

What do you see in these places? (Just ruling out a stray hard return.)

Are you controlling the look of the text by means of clean paragraph styles?

What happens if you patch up to 20.5?

What happens if you export to IDML; re-open the IDML file; and Save-As to a fresh InDesign file? Does the problem persist?

[Editorial-Design]

Thanks for your response.

Yes, show hidden characters on.

Did not view in story editor. What doi you mean by "vault the text"?

I workj in normnal mode, but when the problem occurred started working in Preview where it is difficvult to see my guidelines because Preview mode creates a multitude of gray horizontal and vertical lines from edge to edge on each page. Don't know what that is about.

There is no stray hard return. 

How do you define a "clean" paragraph style? I used therse style and disengage them and reapply them and the problems remain.

I am using InDesign 20.5.0.48 now, but the problem occurred using 20.4.1.

As mentioned in my original post, after much trial and error, the only way I figured out how to fix this was to insert new parent page into the document and flow the same text into a new text frame in the new document page based on the new parent page in the document. Then I deleted the text frame with the bad paragraph line spacing. Corrupted text box, I guess?

I worry that I need to create the document/template from scratch to use the next time I do this project. UGH!

[Eugene Tyson]

Try the Quick Apply - on the top right of the UI there's a lightening bolt symbol.

Type in Recompose All Stories 

And run it. 

See if that helps.

[Editorial-Design]

Apprerciate the idea.

I've never used Quick Apply, and I don't know what it is for or how to use it or why it might thelp.