Editing a Page-Content disappears

Hello. This is a new problem that just started occurring last week. I have several pages on my SharePoint site that I have been editing with new content. When I go into edit mode, everything is displayed on the page correctly. However, if I click into one of the web parts (content editor or script editor) to edit it, the script editors that were below it all disappear. This happens on all of the pages I am trying to edit plus a few additional pages housed on our site. Can anyone provide guidance on how to resolve this issue? Thanks in advance!