close the application
Rename the preferences from the following location
- /Users/[User Name]/Library/Preferences/Adobe InDesign/Version #
- /Users/[User Name]/Library/Caches/Adobe InDesign/Version [#]
then open a new document and then open the document you are facing an issue with it should clear the memory issue temporally
Alternate :
copy and paste the content in a new document and check if the 1st option does not work
PS : changing the folder name would reset the preferences
refer to KB : InDesign preferences and support file locations