Hi back to you and thank you for weighing in.
In "layer options" the option 'hide layers' is not checked. I think everything is visible.
Yes, in menu/object 'show all on spread' is grayed out.
I closed the program, restarted computer and opened the book again. It still shows some pages as completely blank.
I do have a backup strategy - I make a new one every day and then back up to that one all day long. This book is 330 pages with over 500 photos. I think I will go back to the previous backup which seems intact but start making new backups more frequently during the day.
Also, I will check time machine and see if I can figure out when it happened. Honestly, I wish I could just have my own copy of inDesign instead of the online version.
Your input is valued, thank you for taking the time.
You might try exporting to IDML and re-opening that IDML file and saving as a new INDD file (in case of file corruption).
You also might try turning off GPU acceleration in preferences.