In a realm, I was writing a book. During the writing, I noticed that sometimes when I turned a page and then went back the text would remove any enters and paste it all together as one big line of text. 

When editing text with the Paragraph symbol it sometimes turned to ##### for no visible reason. Because the same text on another page was just visible.

When locking the book all text in the book became one big line and half of all text connected to paragraph symbols turned into #####. Just before the locking, all text was just fine. See the screenshots below for illustrations of the problem.

In the realm, there are no resource packs or texture packs installed.