I found that opening 11.3 files with 11.2 occasionally drops actions. I have a client on 11.2 and I am on 11.3. When they opened the files some things were broken. In one case a change of contents action using the new code “Var(PageInChapter) of var(PagesInChapter) gets dropped. Another one was a progress bar with 4 OnOnPageShow actions. the first 3 calculated a % and the last set the progress bar. It dropped the last action. I triple checked and it seems that it happens only going down 11.3 to 11.2, not the other way.
Seems that it changes hyperlink popups too. I had them all opening in a new window, now they open in the same window — about 50 glossary terms.